Please provide instructions and I'd be happy to.
I believe there's an issue with the implementation of DNS in Split DNS Wireguard Client configurations at an OS level, nothing specific to my devices. Like I stated, the config template I shared above works with every other non-GL.iNet client I set up.
This issue has been discussed before on the boards, albeit with this user using Adguard (unsure if they were allowing custom DNS to override VPN DNS: link. It sounds like Bruce may have helped a user with a similar issue, here's a Reddit Post.