considering most Minecraft mods directly mess with the Minecraft code as opposed to going through a well defined API (forge and fabric only provide so much) you can’t really make that work without outright stealing Minecraft code

the best you can make would be resourcepack and datapack compatibility. maybe whatever molang stuff bedrock’s up to

Im not aware of any. Most clones have a very different architecture (and programming language, most clones dont run on the JVM) than Minecraft, even tho some projects go for feature parity and support the original Minecraft multiplayer protocol.

So, no licencing problem Im aware of, mods are free to be shared under whatever licence and many are FOSS, but a technical problem.

I think the other response was quite accurate. Different language and architecture makes it harder. There are mods made for minetest that can work with MineClone2, so there may be some stuff you’ll enjoy, but usually they have to specify it’s available for MineClone2. Here is a page if you want to have a look: https://content.minetest.net/packages/Wuzzy/mineclone2/hub/

Minetest modding is actually quite nice to do from what I’ve heard.

itd be easier to port the mods if anything, since Minetest is meant to be a lot easier to mod and extend than Minecraft. In fact, many of these Minecraft-like games for Minetest are an amalgamation of dozens of individual mods