DV FEL is now working on any DV licensed s905x4 boxes. Because DV FEL only works in CE-NG, this will require creating a new CE-NG USB and using the generic sc2_s905x4_4g_1gbit.dtb.
The s905x4 is not well tested in the CE-NG branch, but it appeared to play all video codecs including AV1 when I tested it.