It is a rabbit hole. I just checked the latest release of GiMP (3.2.4). The "GiMP built-in sRGB" profile is supposed to be a functional match to the ArgyllCMS sRGB color space – the true sRGB profile according to the addendum in the above profile comparison.

But if I embed it in a photo and then open the photo in GraphicConverter, it shows up as "sRGB IEC61966-2.1", which to my understanding is identical to Apple’s sRGB Color Space Profile.icm.

But that's an sRGB v2 profile. Should I download and use a v4 profile instead? Or download the ArgyllCMS sRGB.icm [1] and convert all photos to it? Or just select the Apple default sRGB profile everywhere?

I'm not a pro and don't have a calibrated display, but it annoys me when photos I upload online look vastly different in my browser than they look in my editing software on the same display.

[1] https://argyllcms.com/icclibsrc.html