Display Color Profile Question

I'm using my MacBook Pro 2021 14" and an Acer VG270 monitor to edit photographs. This monitor's color gamut is 99% sRGB. In the Mac OS Display panel, I can choose an Adobe RGB (1998) profile which does affect the color display on the monitor. My questions are:

1. Since my monitor doesn't have the Adobe RGB color gamut, is this just a close approximation? If so, how close?
2. The Mac profile says Adobe RGB (1998) without any explanation. What does the "1998" designation mean? I can't find any info on it on the Apple support site.
3. I assume the only way for this to work is with a monitor that supports Adobe RGB and use a matching profile, yes?

Thanks for your help -

Larry