So I'm playing with a nice community on a realms server and when 1.13 releases, we would like to add some custom recipes to our server. Are datapacks going to work on realms servers? I know that realms is quite limited with the functionality, but this seems like something that should be possible.
It should work, yes. Even now you can already add custom functions and such to a realm by downloading a world, adding the required files and then uploading it. Considering the whole idea with regards to datapacks I wouldn't be surprised if Mojang would eventually add an option to upload individual datapacks which you can then use within the realm. But... that's speculation on my part.
Worst case scenario is to download the world, add the right files and folders and then re-upload it.
I honestly hope that the /datapack command allows you to import functions, advancements, and achievments from other folders/areas of the computer. I hate having to copy/paste my functions in every single world data folder.