Pretty sure you don't need the second GPU for lossless scaling let alone any other GPU. It's a big help in the handheld market with a integrated GPU so one GPU is enough for the app, y'all just reaching it literally does nothing and I'm pretty sure in some cases even made performance and input latency worse. I believe Linus tech tips did this experiment first.
Dual-GPU builds are back, well, sort of. In a recent video, YouTuber ETA PRIME paired an RTX 3060 with an Intel Arc A380 to offload frame generation using Lossless Scaling. Frame generation is a divisive feature: some gamers love it, others hate it. But most would agree that if machine learning can give ageing GPUs a new lease of life, that's a win for the gaming community.