That's the cutest laptop i have seen, after watching it yesterday it made me think about how much work would be needed to get some old netbook like the HP Mini or Asus Eeepc and turn it into a dock for Samsung Dex (desktop mode through usbc->hdmi for Samsung's phones) or a Raspberry pi 4.
The Pinephone comes with a USB gadget driver that presents the phone as a NIC. Plug it into a laptop, and the laptop can then be used as a terminal for the phone simply by sshing into it. X forwarding works, so you can practically run desktop programs that would be cumbersome to run with a touchscreen.
You could probably do the same with a Raspberry Pi, but it might be trickier to do with an Android phone. A phone that supports Termux or UserLAnd would work well if you used adb port forwarding.
Why not get something like a HP Pro Tablet 608 G1? It is a slim 8" and it has 5g wifi. That is about the size of the libretto 50ct that I used to have, but the user isn't stuck with Win98se2.