This is a gray area. Some "cooked" ROMs are not true custom ROMs but modified EMUI packages that re-enable Google Push Notifications and remove Huawei ID restrictions. They perform a "downgrade" to EMUI 10.1, spoof the device ID, and inject Google Play.
LineageOS is the gold standard for clean, bloat-free Android. Custom Rom For Huawei P40 Pro
SuperCharge (40W) usually works, but wireless charging can be buggy. Unlocking Freedom: The Ultimate Guide to Custom ROMs
After weeks of development, testing, and refinement, Alex's custom ROM for the Huawei P40 Pro is ready. The ROM, dubbed "P40 Pro X," offers: LineageOS is the gold standard for clean, bloat-free Android
Which would you like?
. If you manage to unlock your bootloader, you could theoretically run AOSP-based GSIs, but hardware features like the advanced camera sensors often lose optimization. OS Alternatives