Er? Android supports multiple VPNs at the same time on the same user profile? Since when exactly?

Whoops, unfortunate typo, meant to type "not". My issue was I already used the Mullvad VPN client, so I couldn't double-up with a personal wireguard VPN client for my homelab. Tailscale "solves" this by supporting mullvad exit nodes natively in the service via a direct partnership, so you can have "one" VPN with multiple nodes accessible.