1080p Blu-Ray copies would certainly be doable, but I don’t know of anyone (including the members of the 4K77 forums) who is capable of authoring and burning a 4K Blu-Ray that is playable in a standalone player. I for one put my 4K copies on a flash drive to plug directly into my TV and watch them through my TV’s built in media player software. Most UHD BR players are capable of this as well.
May I borrow your flash drive? lol