How about BananaWRT for BPI-R4?

[GrampusV]

An excellent, well-balanced operating system, not overloaded with complex details. The R4 platform is no less popular than the R3-mini and also requires support from a similar operating system build. I'll mention a couple of common platforms: ASIA RF AW7916-NPD or be14 + R4 + FM350-GL

[SuperKali]

Thank you, I am waiting for my Banana Pi R4 to be delivered, as I had to send it in for repair due to the fragile SIM slot. Before integrating that board, it should at least be stable and functional on immortalwrt. Creating patches would take a long time, and I currently have very little time due to work.
I manage BananaWRT as a hobby in my spare time; I do not earn any income from this project.

[GrampusV]

I understand your point, but I'd like to thank you for sharing your practical work in open source. Thank you, I'll be following your project, as will many in our community.