The question is where I should currently be posting things concerning Datapacks?
The suggestion is making a category on Minecraft forums for Datapacks.
Datapacks are posted in the Mapping and Modding forum section. For a list, you can just click this link. I've applied the filter so you can see. Depending on what it is, you could post in two places. If you need help installing a datapack/technical assistance for it, you can post in the Mods Discussion forum again with the datapack tag. Again, this section is great for asking questions about datapacks. If you need support though, you could post in the Java Eddition Support section. This section would be great for if you're not able to launch or problems that could come from other things besides the datapack.