I use Aegis for important apps and store all non-critical ones in vaultwarden. It’s a good trade-off in my opinion of having the convenience for less important things but still be secure and not having a single point of compromise for my critical, sensitive apps.
If you want to use transmission as your torrent client I recommend checking out https://github.com/haugene/docker-transmission-openvpn . There are some additional configuration changes needed for mullvad but it should be straightforward.