1) Get a title id of any game you have installed from
http://switchbrew.org/index.php?title=Title_list/Games (this is your target titleid)
2) Create a directory on SD : sd:/atmosphere/titles/*target_titleid*
3) use hactool to extract the romfs.bin and exefs files from your main game nca (its in secure from XCI - the biggest one)
4) put romfs.bin in sd:/atmosphere/titles/*target_titleid*/romfs.bin, exefs files into sd:/atmosphere/titles/*target_titleid*/exefs/
5) Edit titleid in main.npdm (in exefs) to contain target title id (this might help
http://switchbrew.org/index.php?title=NPDM)
6) run a fs_mitm containing CFW release, run your target app (
https://gbatemp.net/threads/how-to-get-layeredfs-working.507460/)
Note that saves don't work for me atm, you should wait for mememenu/similar.
Minecraft works, others not tested.
proof video: