I'm not sure if you have access to previous frames in RA shaders, you get a frame index at least, maybe there's some option / way to feed old framebuffers, the

I'm not sure if you have access to previous frames in RA shaders, you get a frame index at least, maybe there's some option / way to feed old framebuffers, the docs are a bit lacking. But yes, RetroArch emulation cores, the Analogue FPGA systems and IIRC even replacement IPS screens for GameBoys address this particular issue. I can't really tell you how good of a job they do, I mostly play GB(C) on my unmodded GBC. But I also run GB games on my CRT emulation setup through RA and I definitively played some of the problematic games that use the slow display response for additional shades or fake transparency and I can't say I noticed anything wrong. There are options to control frameblending etc. in the emulator specific options, but I haven't spend any time tweaking them.