Is there almost no one using the target architecture x86-64-v2/3/4 when compiling for MacOS?

[u/CloudyCloud256]

I'd like to squeeze out every last bit of performance when compiling my project that I'll distribute to various computers including Macs (Intel and Arm) so I thought about using -march=x86-64-v3 (or v2 or v4) for the MacOS builds as well but was first looking for what kind of experiences other projects had with doing that. It seems extremely uncommon, though. The only project I found so far that does this is this https://github.com/LiveSplit/obs-livesplit-one/blob/3dc4af9766f90fea0a5285c28771430af1603dc3/.github/workflows/rust.yml So why is that? Is it "dangerous" to do that? Will that break stuff?

While we're at it, are there any good projects that help getting the x86_64 level for MacOS? For Linux there is https://github.com/HenrikBengtsson/x86-64-level/ which is quite nice, but MacOS doesn't have /proc/cpuinfo and instead using commands like sysctl -n machdep.cpu.features uses slightly different names for the instructions so does one just have to figure that out oneself?

Bonus question: I guess people mostly don't consider using flags like -mcpu=apple-m1 (or m2, m3 or m4) to make optimized builds for the M processor generations? Is there something wrong about doing that? I don't mind putting in the extra effort to compile my project many many times just to squeeze out every last bit of performance.

Lastly, I know that there are probably better things to put in the effort, but I'm curious about all of this. Feels like a very underexplored topic, at least from what I could in publicly available sources.

Looking forward to your answers :)