Kant you kome up with something kool

Yes we kan!

Install Ventoy on internal hdd.

https://www.ventoy.net/en/doc_non_destructive.html

I have a folder called ISO on my hdd. I just drop an iso there and reboot into ventoy.

I also added ventoy to my grub, but it was pretty hacky, something like adding the uuids of ventoy and my data partition.

You can even boot some isos directly from grub without ventoy.

Dell latitude 5285 is a very robust tablet, its old af but has an x86 intel cpu (i5 or i7 7th gen, rather slow, but fast enough for office and yt) and its easily repaireable (screws on the back) so new battery is no problem.

Refurbished they are sometimes available for ~200€ in germany

Only real issue i found was: volume buttons only work in x11 not in wayland