I don’t use radicle yet, but from what I understand I don’t see how it would change anything connectivity wise for your team. If you have private repos you self host in a company server, radicle would behave exactly the same. You would still not want it exposed publicly and would still need the VPN.

If anything, you could be less safe since a miss configuration would mean Radicle publishing, and potentially many others seeding, your private repos.

It is rare, very rare, to find anything like this with Mercurial support. Same for services.