Lenovo Pad if you order the unlocked versions from Aliexpress. Search for Xiaoxin Pad, anyone offering a global ROM version has unlocked the bootloader.
I also have a Pinetab 2 and now after a year I'd say it's in a pretty good state.
However, if you just want a tablet, a similarly priced Android tablet will run circles around it in responsiveness and feel. (I have a Xiaoxin Pad pro 2022/Lenovo Pad M10 3rd gen)
Re RISC-V: AFAIK the new SpacemiT chips are the first actually usulable ones. The older and more common JH7110 has half the cores and way lower feature level. Like, no floating points and other extensions that are essential for modern computing.
Not sure how well it works, but this already exists with mCaptcha