Four thoughts are:
1 Do I really need it?
Realistic options:
2 Get a 5/1/0.1W Guitar head like those in my first post and tweak the tone capacitors to get a more bass-gutar focused response. Main drawback, maybe too much distortion, (maybe) weak bass.
3 When my workshop is sorted, build an amp around a twin 6J1 board (cascade the two stages, use plenty of input gain to overdrive the valves) that I already have (somewhere) as preamp driving a conventional back end.
https://hackaday.com/2020/09/01/that-elusive-valve-amp-sound-for-not-a-lot-there-has-to-be-a-catch/
4 Get the Hotone, actually it's quite appealing and not a big price tag.