Restricted groups are tricky but a paid relay + nostr:nprofile1qqsf03c2gsmx5ef4c9zmxvlew04gdh7u94afnknp33qvv3c94kvwxgsppemhxue69uhkummn9ekx7mp0qy2hwumn8ghj7un9d3shjtnyv9kh2uewd9hj7qgewaehxw309a5xyu3wvdhhyctrd3jjuum0vd5kzmp0gankr4 's flotilla (Discord-like) client could be a nice solution. Its easy to get a relay from nostr:nprofile1qqs8eseg5zxak2hal8umuaa7laxgxjyll9uhyxp86c522shn9gj8crspz9mhxue69uhkummnw3ezuamfdejj7qgjwaehxw309ahx7um5wgerztnrdakj7qgkwaehxw309a3x2an09ehx7um5wgcjucm0d5hsvlnggv 's https://relay.tools/

https://flotilla.social/