[ubuntu] confused with Xen install into existing ubuntu

I'm trying to learn docker through a course. During the course you need VMs. I know the easiest way is Virtual Box, but I know that Xen is the basis of all container technology (if I understand it correctly). So if I can do it that way, I would like to. My machine, is a few years old but has plenty of processing power. Less disk space than I would like.
I've read a little bit about how a hypervisor works, but at the practical use level, I'm confused. Is Xen headless, I know it can be, but does it force it? I can't follow the instructions exactly from that link, because I'm already on Ubuntu. It came that way from Dell. I don't want to bother doing a full reinstallation of everything right now. I want to complete my course, preferably with Xen.
I can't do "During installation of Ubuntu"... I did install Xen and tried to reboot, and got the no signal. Is that normal, or because I missed something in the order of operations? I did go through and enable everything I saw in the bios for virtualization. When googled I found (https://askubuntu.com/questions/1317...r-installation) which had no useful responses.
I've been reading various web pages, but I'm a bit confused. Most say just install, reboot, then

https://help.ubuntu.com/community/Xen

I've been trying to check somethings from other pages, but I'm still confused.


%sudo apt search grub|grep "^grub"|grep "installed"
grub-common/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic]
grub-efi-amd64/jammy-updates,jammy-security,now 2.06-2ubuntu14.1 amd64 [installed,automatic]
grub-efi-amd64-bin/jammy-updates,jammy-security,now 2.06-2ubuntu14.1 amd64 [installed]
grub-efi-amd64-signed/jammy-updates,jammy-security,now 1.187.3~22.04.1+2.06-2ubuntu14.1 amd64 [installed]
grub-xen-bin/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic]
grub-xen-host/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic] grub2-common/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic]

% sudo apt search grub|grep xen
grub-xen/jammy-updates 2.06-2ubuntu7.2 amd64
grub-xen-bin/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic]
grub-xen-dbg/jammy-updates 2.06-2ubuntu7.2 amd64
grub-xen-host/jammy-updates,now 2.06-2ubuntu7.2 amd64 [installed,automatic]

boot directory
$ ls -larth /boot/
total 355M
drwx------ 4 root root 4.0K Dec 31 1969 efi
-rw-r--r-- 1 root root 8.0M Apr 29 2019 vmlinuz-4.15.0-1037-oem.efi.signed
-rw-r--r-- 1 root root 181K Feb 6 2022 memtest86+_multiboot.bin
-rw-r--r-- 1 root root 181K Feb 6 2022 memtest86+.elf
-rw-r--r-- 1 root root 179K Feb 6 2022 memtest86+.bin
-rw-r--r-- 1 root root 1.2M Nov 26 2022 xen-4.16-amd64.gz
-rw-r--r-- 1 root root 2.7M Nov 26 2022 xen-4.16-amd64.efi
-rw-r--r-- 1 root root 2.2K Nov 26 2022 xen-4.16-amd64.config
-rw------- 1 root root 6.0M Aug 14 04:05 System.map-5.15.0-83-generic
-rw-r--r-- 1 root root 256K Aug 14 04:05 config-5.15.0-83-generic
-rw------- 1 root root 12M Aug 14 04:07 vmlinuz-5.15.0-83-generic
-rw-r--r-- 1 root root 154M Sep 5 06:32 initrd.img-5.15.0-83-generic
-rw------- 1 root root 6.0M Sep 5 08:31 System.map-5.15.0-84-generic
-rw-r--r-- 1 root root 256K Sep 5 08:31 config-5.15.0-84-generic
-rw------- 1 root root 12M Sep 5 11:57 vmlinuz-5.15.0-84-generic
lrwxrwxrwx 1 root root 25 Sep 20 06:38 vmlinuz.old -> vmlinuz-5.15.0-83-generic
lrwxrwxrwx 1 root root 25 Sep 20 06:38 vmlinuz -> vmlinuz-5.15.0-84-generic
lrwxrwxrwx 1 root root 28 Sep 20 06:38 initrd.img.old -> initrd.img-5.15.0-83-generic
lrwxrwxrwx 1 root root 28 Sep 20 06:38 initrd.img -> initrd.img-5.15.0-84-generic
drwxr-xr-x 5 root root 4.0K Sep 20 06:39 grub
-rw-r--r-- 1 root root 154M Sep 25 11:13 initrd.img-5.15.0-84-generic
drwxr-xr-x 4 root root 4.0K Sep 25 11:13 .
drwxr-xr-x 23 root root 4.0K Sep 27 13:04 ..

Sorry didn't paste right
# # Automatically generated file; DO NOT EDIT. # Xen/x86 4.16.0 Configuration # CONFIG_CC_IS_GCC=y CONFIG_GCC_VERSION=110300 CONFIG_CLANG_VERSION=0 CONFIG_CC_HAS_VISIBILITY_ATTRIBUTE=y CONFIG_X86_64=y CONFIG_X86=y CONFIG_ARCH_DEFCONFIG="arch/x86/configs/x86_64_defconfig" CONFIG_INDIRECT_THUNK=y CONFIG_HAS_AS_CET_SS=y # # Architecture Features # CONFIG_64BIT=y CONFIG_NR_CPUS=256 CONFIG_PV=y # CONFIG_PV32 is not set CONFIG_PV_LINEAR_PT=y CONFIG_HVM=y CONFIG_SHADOW_PAGING=y # CONFIG_BIGMEM is not set CONFIG_TBOOT=y CONFIG_XEN_ALIGN_DEFAULT=y # CONFIG_XEN_ALIGN_2M is not set # CONFIG_XEN_GUEST is not set # CONFIG_HYPERV_GUEST is not set # end of Architecture Features # # Common Features # CONFIG_COMPAT=y CONFIG_CORE_PARKING=y CONFIG_GRANT_TABLE=y CONFIG_ALTERNATIVE_CALL=y CONFIG_HAS_ALTERNATIVE=y CONFIG_HAS_COMPAT=y CONFIG_HAS_EX_TABLE=y CONFIG_HAS_FAST_MULTIPLY=y CONFIG_HAS_IOPORTS=y CONFIG_HAS_KEXEC=y CONFIG_HAS_PDX=y CONFIG_HAS_SCHED_GRANULARITY=y CONFIG_HAS_UBSAN=y CONFIG_MEM_ACCESS_ALWAYS_ON=y CONFIG_MEM_ACCESS=y CONFIG_NEEDS_LIBELF=y # # Speculative hardening # CONFIG_SPECULATIVE_HARDEN_ARRAY=y CONFIG_SPECULATIVE_HARDEN_BRANCH=y CONFIG_SPECULATIVE_HARDEN_GUEST_ACCESS=y # end of Speculative hardening CONFIG_HYPFS=y CONFIG_HYPFS_CONFIG=y CONFIG_IOREQ_SERVER=y CONFIG_KEXEC=y CONFIG_XENOPROF=y # CONFIG_XSM is not set CONFIG_SCHED_CREDIT=y CONFIG_SCHED_CREDIT2=y CONFIG_SCHED_DEFAULT="credit2" CONFIG_CRYPTO=y CONFIG_LIVEPATCH=y CONFIG_FAST_SYMBOL_LOOKUP=y CONFIG_ENFORCE_UNIQUE_SYMBOLS=y CONFIG_CMDLINE="" CONFIG_DOM0_MEM="" CONFIG_TRACEBUFFER=y # end of Common Features # # Device Drivers # CONFIG_ACPI=y CONFIG_ACPI_LEGACY_TABLES_LOOKUP=y CONFIG_NUMA=y CONFIG_HAS_NS16550=y CONFIG_HAS_EHCI=y CONFIG_HAS_CPUFREQ=y CONFIG_HAS_PASSTHROUGH=y # CONFIG_IOMMU_QUARANTINE_NONE is not set CONFIG_IOMMU_QUARANTINE_BASIC=y # CONFIG_IOMMU_QUARANTINE_SCRATCH_PAGE is not set CONFIG_HAS_PCI=y CONFIG_HAS_PCI_MSI=y CONFIG_VIDEO=y CONFIG_VGA=y CONFIG_HAS_VPCI=y # end of Device Drivers # CONFIG_EXPERT is not set # CONFIG_UNSUPPORTED is not set CONFIG_ARCH_SUPPORTS_INT128=y # # Debugging Options # # CONFIG_DEBUG is not set # end of Debugging Options