nostr:npub1wcf6srj73muaspe5hvyve6af6ep236xzqvfepr6j4vut4c8nkj6swtequk for xmpp you can install gajim on pc and blabber on mobile (i'd recommend just on your phone if you won't use it much)
for matrix you can just install element.io (or use the webapp at app.element.io), element is simple enough my grandma figured it out on her own