The folk who left Psion tried to resurrect the Psion 3/5 form factor a few times as an Android phone with a fairly decent keyboard, but I don’t think they’re still around (or that it’s cheap enough to justify getting one).

I think the F(x)tec Pro1 might fit the bill, but getting it to run real linux might be a challenge.

Planet Computers Astro Slide 5G also sounds like it could work.