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
I dont know about that, most phones dont do boot over usb. But some Volla Phones support dual boot from internal storage.
X23 for example: https://volla.online/de/volla-phone-x23/