New builds are up with revised 5.10 patches from @rsalvaterra and the DSA/FDB fix patchset updated for 5.10 thanks to DENG Qingfang.
They do not contain WireGuard, until PR3885 is ironed out.
Please test them.
I've got both my units running it with no issue so far.
For those building, I suggest you drop all patches, and apply the 20 from here.
You can choose 5.4 or 5.10 under Global build settings > Use the testing kernel version.
Have fun!