A bit late to the party, but here's my input:
I'd say the whole plan sounds good. I've wanted a resource pack slot for a while although since in my datapack the resource pack is optional to use (because all it does is allow you to play my datapack in other languages, meaning if you just play in English you won't need it) maybe add a checkbox for saying whether or not the resource pack is required?
Also additionally I'm a bit unsure which category I'd choose to use for my advancements datapack since it pretty much only adds advancements (maybe game mechanic?). I know some other datapacks only add recipes or loot tables (which would fit under "Quality of life") and some only structures (fit under "Adventure"). So I know for projects there's long been a category called "Challenge/Adventure" so maybe a category like that.
Also I saw in another comment by Hashs that their suggestion for a category is "Some kind of category to represent a large amount of varying content," (cause it is theoretically possible for a datapack to add many new custom mobs, blocks, mechanics and structures to the world generation) I think a good name for this category might be "Overhaul" (namely meaning the datapack largely overhauls the vanilla gameplay experience) or maybe a less intensive name like "New Content" or just "Content" (which just implies the datapack adds some [but not a lot] of new content to the game.)
(Off-topic, but speaking of categories, I kind of feel like the categories for "projects" needs a huge update/overhaul due to a lot of people making custom maps and most custom maps either only fit into "Challenge/Adventure" or "Other" since most of the categories only describe what the project is visually. Plus many maps have a huge mix of structures. But that's for another day)
