Also... It is very customizable with good a 100% graphic UI.

As an alternative to ventoy, can I use refind on a usb flash drive with iso images?

More a Dell thing than refined I believe.

I just have to remember to delete the UKIs manually when I uninstall the corresponding old kernel package, otherwise the EFI partition would fill up eventually. If my distro ever switches to UKIs by default then the postuninstall script would handle that automatically.

I noted recently that it also sees systemd-boot installations and will boot from those, if desired (in my case it was a fresh installation of Pop OS, which uses systemd-boot by default).

For me, it's unambiguously better (meaning easier, with no extra periodic steps required to maintain my ability to boot whatever bootable thing I want), but I am curious about what scenarios would make one want to use systemd-boot (or grub) instead.

I have Linux VMs which boots in ~2s (to ssh login; ~700ms to userspace). I use systemd-boot because it has nicer integration with my distro of choice than bare EFI stub, and it adds very minimal overhead in boot time.

Use linux-image-cloud; use a modern hypervisor with no legacy devices (only virtio etc); use tiny-initramfs; mask systemd-networkd-wait-online.service; add cryptomgr.notests noreplace-smp to kernel command line.

I think that's all, and use a moderately fast CPU (i7-8700K which is already 5 years old).

When you say modern hypervisor, do you mean, not KVM? How do you get around the UEFI/BIOS post time which is usually a few seconds by itself?

I'm talking about the time taken by OMVF/SeaBIOS or whatever equivalent in the VM; which is why I asked about the type of VM/Hypervisor because that might not apply.