There are no right or wrong answers to this. It can be pro-rated for the cost of living, pro-rated to the cost of market (GitLab approach) or just a standard rate that's below SF market.
You can pay $60k to a senior engineer in an emerging economy and he/she will be super happy about it because that is way above market in his/her country. Regardless of which method you used to get to that number.
I'm all about paying above market rates, you get what you pay for and it's not a linear scale, probably more like an activation function.
There is an interesting idea that seems to be working well. That is salary transparency. Everyone in the company knows how much everyone else makes. It instantly removes gender / race / negotiation skills as a difference maker. Geography seems like it would benefit, and that some amount of cost of living adjustment ought to be incorporated, though perhaps how you do this encourages behavior in some direction.