I use Lorys89's EFI with every kext updated and the latest OC, and I have recently updated to 15.6. The difference is that for Sequoia I've replaced AirportItlwm with itlwm/Heliport. Everything seems to work except Bluetooth LE, which is a bit of a nuisance as I can't use my MX Anywhere 3S. Bluetooth works with non-LE devices, which is OK for now.
I see @Lorys89 has recently posted a link on GitHub with updated kexts for BT, but I couldn't boot after replacing IntelBTPatcher, and I didn't have the time to review the logs.