I've done exactly this with wg-easy so I can use my external VPN on my phone while still connecting to my home network without toggling VPNs.
My config here is for v14, you'll want to pin the image version: https://github.com/qdm12/gluetun/discussions/1192#discussioncomment-12973135 Note there's a small typo in the local network Down rule I added, I'm on mobile right now else I'd copy my current config instead that cleans it up a bit since this post.
In the same thread, someone posted a fantastic guide to get it working with v15. You'll need to add an iptables rule for full LAN access if you want to enable that: https://blog.bktus.com/en/archives/2918/
V15 was giving me issues because it didn't allow you to disable ipv6, but apparently the latest edge builds do. I haven't tried that yet