Available from XDA Developers, Custom ROMs benefit devices from various brands including ASUS, HTC, Motorola, Xiaomi, Redmi, OnePlus, Samsung, and others, covering over 70 upgradeable devices (as is the case, for example S10e, S10 and S10 Plus) and also, devices already abandoned by manufacturers (case of Pixel and Pixel XL).
Below you can see the full list and access all ROMs related to the devices in question by accessing the post that compiles everything from XDA Developers.
So, is your device one of those available to use Android 11 based custom ROM? Tell us in the comments!
(updated October 18, 2020, 1:44 p.m.)