1. It should be compatible if they are using the standard protocols. For OpenVPN, we need the .ovpn files. IKEv2, server certificates (if they use self-signed certificates). For WireGuard, you’ll need the server hostname, public key, and the client private key.
2. We’ll restock our hardware soon, in the next week or two.
We don’t know about the sites you mentioned. Please check back with us in the next few days.