I recently picked up an older MS Surface model and it has been really good. I don't know where tablet bleeds into 2in1, but it's a tablet that has a magnetic keyboard that pops on and off and accepts USB connections for stuff like mice with a USB to USB-C adapter or via a surface dock. Prices start at around $70 on ebay for older models in decent condition and run up to around $2k for the highest end models directly from Microsoft. Being x86 they accept any compatible OS (including Linux) and installs just as easy as any laptop (minus the later models that need the touch driver installed manually on Linux or a Windows re-install). If you go with a surface and buy an older model make sure you get 8gb of ram instead of 4.

As far as setup goes, I went with Gnome, enabled the on screen keyboard, then added the "custom hot corners" Gnome plugin to get a working on screen keyboard everywhere (without the plugin it only works in Gnome and Gnome apps). Afterwards (since I went with an older model that didn't need the touch drivers) it's fully ready for use like any other device.

There's also the PineTab2, though from the sounds of it it's not really ready to be used as a tool, more so just for development and experimentation. I did find two good blog posts about it's state when researchign devices which would be worth reading if you were considering buying a PineTab2 and wanted to know what to expect:

https://ivonblog.com/en-us/posts/pine64-pinetab2-review/

https://ivonblog.com/en-us/posts/after-3-months-of-daily-driving-pinetab-2/