There's already OpenVSX (https://open-vsx.org/) maintained by the Eclipse foundation, and it contains almost all of the mostly used FOSS extensions (not the propietary Microsoft extensions though). It's used by default in VSCodium (FOSS version of VS code), and also Eclipse's own cloud editor Theia (https://theia-ide.org/).
I hadn't heard of this! Thank you! My VSCode experience is primarily "VSCode" (not Codium) w/ the MS Remote extensions and looking at code-server for its more unique capabilities. Definitely going to look into this and adopt it where I can.
FYI, it looks like the code-server devs have some concerns about # of extensions and matching the MS market: https://github.com/cdr/code-server/issues/1473 . I'm not too worried about that for myself though.