Yes theres absolutely tools to convert mc worlds to minetest/luanti worlds. using these tools probably requires some willingness to run terminal based shell commands though.

https://github.com/minetest-tools/mcimport

Have you been keeping tabs on the mineclone projects these past few years? Mineclonia and voxelibre are both excellent Foss alternatives. Most people would struggle to be able to identify MCLA with a MC texture pack as any different from real deal.