I am a big fan of Self-Hosted FOSS.
I enjoy helping seniors understand new technology. 
FOSS Software Favorites (in no order)
Ubuntu, Kodi, Nginx, Postfix, Dovecot, RoundCube, Nextcloud, Collabora, Jellyfin, Passbolt, Mastodon, PostgreSQL, MySQL, Discourse, WireGuard, OpenVPN, ClamAV, Thunderbird, Firefox, Fail2ban, UFW, Bind9, WSJTX.