Leaderboard

No, there's nothing else known to drain a battery, except the heavy graphics-oriented nature of the OS. Maybe you ought to reconsider your UEFI method and switch to SSDT to disable (=power off) your dGPU. That's a guaranteed method.

boot with verbose + debug 0x100 mode to help determine where the issue is. Also read here for Catalina requirements to have a successful upgrade / installation

You can just do a quick google search for lilu kext, then whatevergreen kext, that will take you to the GitHub site where you can download the latest versions. Put these in your Clover/Kexts/Other folder, and replace the existing kexts. Lilu Whatevergreen.zip