@jppelt Hiya

>Given support is all in Japanese

I also don't speak/read Japanese, & atm #Firefox [ergo, also #Floorp]'s #Translate tool sadly omits Japanese. This was part of the reason in one of my toots yesterday i opined the idea of a sub-community of putative or actual #Floorpers here in the #Fediverse, for mutual troubleshooting / support / fat-chewing.

>NOT comfortable giving my Firefox login to a third party

Fair enough. Fwiw, i utterly eschew ALL browser synching everywhere in all circumstances, so your dilemma hadn't crossed my mind before.

>Vivaldi'esque aesthetic

Yes! So far, afaik, it comes closest for #Gecko / #Firefox forks to #Vivaldi's wonderful options & flexibility, but importantly without the damn #chromium baggage.

>How do I get rid of the sidebar?

Oh really? You don't like it? OK. For me this is a major asset which entirely elevates #Floorp [& #PulseBrowser, albeit it's much less flexible & optionable] above plain FF, & which i always enjoy each time i use Vivaldi, then badly miss when using FF.

Anyway, try this, in `about:preferences#bSB`.