Data Packs - Support for entities, blocks and items, with their own IDs

In Bedrock Edition Behavior Packs we have the ability to create custom Items, Blocks, and Entities. I understand that this is possible in Java Edition with mods, but Data Packs really have potential. (In my case, my friends and I have a server with Data Packs because our PCs aren't big enough to run mods.) I'd really love for it to be possible. I'm not going to make this post any longer because I really don't have anything else to say. I hope you consider it :)