The vanilla game provides feature toggle datapacks, as well as programmer art and high-contrast resource packs. Mods can also provide optional resource packs, and I believe also optional data packs. It would be nice to be able to auto-enable those with this mod.

Fair enough; my main goal when suggesting this was to force-enable bundles and then I had scope creep when making the request.

I can take a look at the optional vanilla packs, but I don't think I'll be able to do the same for mods.
There is no real standard to my knowledge that works across all modloaders, and I am not willing to make features that will only ever work for one modloader.

Custom datapacks can also enable feature flags, you'd still have to provide the recipes though.
I think that feature is part of the .mcmeta?

Oh, yeah, I read that when the feature toggles first came out but I forgot. Thanks