As long as you onboard them with the ElementX/SchildichatNext(better fork of element) mobile client, their experience and setup should be fairly future proof. Its still changing and growing for sure but the most important stuff is finally working now and the new call systems is a huge improvement.
But yeah if you want zero metadata, your only choice is P2P stuff like Briar.
Oh noo but i thought it was only the evil chinese deep seek that was insecure garbage.