I put a post in the mod forum to see if Pine still have any of the Android IMGs and can make them available for download again. Hopefully the deads links are just an oversight from the last server issue and the IMGs can be restored to their links. I'd offer to check the NVME in my PBP for any, but I know those would all be for the PBP or the A64.
Looking again, it does seem that this android repo does include the rk3399 in its manifests. unfortunately it's a nougat img, so it's quite behind, and appears to require compiling/building yourself.
EDIT: asked on the #rock64 channel if anyone had any of the previous IMGs, and @gamiee was kind enough to upload some of the imgs they have. If there's a specific one you're looking for, that isn't available now, you can try asking them if they have it.
Looking again, it does seem that this android repo does include the rk3399 in its manifests. unfortunately it's a nougat img, so it's quite behind, and appears to require compiling/building yourself.
EDIT: asked on the #rock64 channel if anyone had any of the previous IMGs, and @gamiee was kind enough to upload some of the imgs they have. If there's a specific one you're looking for, that isn't available now, you can try asking them if they have it.