Any quality documentation on how to do this would be great.
As a concept, Frida works by running a gadget on the phone (as root, or as part of an app) and a client on another device (or the same device, I suppose, if you're using a terminal emulator on Android).
To install the gadget, you either download the right binary and execute it on the phone as root, or use a tool like https://github.com/ksg97031/frida-gadget to inject the gadget into an APK.
Then, use Frida (https://frida.re/docs/Android) to connect to the gadget and load any script you want. There are a bunch of scripts that can be used to patch out certificate validation, or to exclusively use a certificate authority of your choice, or you can write your own.
You can download scripts and run them directly, or you can run Frida with a command line flag to open up a remote debugging port; you can connect to that port from the Chrome dev tools and get an interactive code execution prompt. From there, you can patch out Java methods, load native binaries, patch memory, whatever you want. It's a really powerful tool for debugging and reversing applications you don't have the source for.
Not much I can do with that data, other than sleep in comfort knowing that its the case.
There are plenty of pay2win games out there, but if the game doesn't tell you that paying will give you an unfair advantage /or what advantage you're getting, exactly) I'd consider that worth reporting on, especially if the game has a decently large following!
Alternatively, you can use ADB + Frida to pull an APK from the device, inject a binary, and inject code at runtime using Javascript or Python. That's much easier for intercepting traffic than messing with certificate stores or eBPF ever was in my opinion.