It can be a bit rough around the edges, and I can't compare it to Minecraft, but my mid-range phone runs it at a stable 60 FPS without breaking a sweat.
If you install the "MineClone2" game from within Minetest, the gameplay is quite similar to Minecraft, too.
As the other guy said, it's not Minecraft, and not trying to be compatible with it, so no. There's some hacky scripts for converting Minecraft maps and texture packs, but that's about it.
Minetest does have a surprisingly active modding scene of its own, so if you're open for a different experience, I do think it deserves a look. And logging onto a Minetest server is a great way to discover lots of mods, as the client will automatically download and apply the mods from the server.
Nah, definitely not the Java mods. Because Mojang never introduced a modding API, the Java mods just directly fuck around in the Java code of Minecraft itself. And that requires the Java code of Minecraft itself to be there and running.
It's more viable with Bedrock edition mods, I assume, but of course, that's much less useful...