Question about VPN in Docker

What's the best practice for keeping everything behind a VPN? I'm running Ubuntu and have PIA installed outside of Docker. I want to for sure run qBittorrent and Prowlarr through a VPN. I was able to set up Gluetun and connect my containers to it.

I'd like to mirror my Windows set up with PIA installed, kill switch enabled, qBittorrent assigned to PIA network adapter only. I'm not sure how the network adapters work when qBittorrent is inside a container and PIA is outside.