Your question,Perhaps only professionals from StarFive can provide answers, please wait for their response.
I am just an old user of VF2. My personal guess is: 4k@60 This is the highest parameter that VF2 hardware devices can achieve,But now, many of the supporting software for the RISCV architecture are not yet complete, including drivers and operating systems.
You can try upgrading debian2409 to debian13, It may not necessarily solve your problem, but you can experience the new support for both Risc-v and Wayland.
Upgrade to debian13, you can refer to here, Debian2409pro is an unofficial image, which is pre prepared for upgrading on Debian2409. You can easily upgrade to Debian13 with it and keep the GPU VPU running normally.