Turning on the mics and feeding to headphones (even with voice boost), has been trivial for a while. It could have been implemented a decade ago, no?

I can understand that position, but in practice I don't think you'd like the quality.

One of the big advantages of hearing aides is that they have multiple microphones that have known alignment with your head position. With all 4 mics separated in space, they do a good job of isolating audio coming from in front of you vs from around you.

Plus people can lose hearing in different bands: they might hear bass fine but people with high-pitched voices may not register. Just turning up the volume won’t address that.

Maybe, maybe not. Noise canceling with multiple mics is old tech. As far as anyone knows, no one ever tried.

Maybe I’ll try with my pine phone if I can figure out pipewire programing.

Yeah, when you get into what hearing aides do, there's quite a bit going on.

This manual is a useful place to start: https://order.starkeypro.com/pdfs/The_Compression_Handbook.p...

The FDA regulations allowing for OTC hearing aids didn't go into effect until a little under two years ago, so regardless of the technical feasibility, the market viability of what you're asking for is a recent thing. (Though since using wired headphones with smartphones has been in decline for well over two years, the market viability is still questionable at best.)

It’s a couple of lines of high-level code on hardware that already exists. Doesn’t need market viability or regulatory approval.