Actually, my mother knew how to use Debian before she could use Windows. Her first pc came with Windows XP, switched that for Debian as its been my main OS since 2000.

Yes, you can teach your grandmother to use Linux.

With wireguard i set up an easy VPN, then vpn to the home network and use jellyfin.

If i cant use vpn, i have Jellyfin behind a caddy server with automatic https and some security settings.