Expose Overseerr over HTTPS either from your home network or on a free VPS which has the tunnel into the home network where Radarr and Sonarr live. This is simpler for users to go to a website instead of having to also use a VPN.

This of course assumes you already have Plex or Jellyfin exposed to the public internet without a VPN.

If you're already forcing users to use a VPN for Plex/Jellyfin then hosting Overseerr locally and making it accessible over the VPN should be trivial.