EF'ers, have any of you as British citizens with Swiss residency (not citizenship) attempted/completed a permanent move to France since Brexit kicked in?
You might try asking in this Facebook group: https://www.facebook.com/groups/Expats.Alsace
There is a FB Forum called 'The France Forum' too. Most of them live in SW or the Côtes.
That's why I proposed the Alsace forum -- they are more likely to have people with experience from changing from a B/C-permit to a G-permit on the Swiss side, and the process and eligibility criteria for requesting a carte de sejour from the French authorities. The Venn diagram of post-Brexit cross-border British frontaliers (not married to an EU citizen) is likely to be a pretty niche group.