There's this hashrate distribution chart, but that shows only the pools.

Hashrate Distribution Historical Chart https://insights.braiins.com/en/pools-blocks/

Knowing the geographic distribution of the actual hashrate, is much more difficult. CBECI attempts it, but there are a lot of assumptions that may not be accurate with their methods as well.

My pool doesn't know what I do with my payments after they've sent them to me, and if I had sold, my centralized exchange (if I sold coins using that method) wouldn't know that the coins came from mining.

So there is little to no information available to you to be able to tell if miners are selling -- at least for a good chunk of the global hashrate.

Now there is that info from the publicly traded miners as they report that info in their quarterly reports. Many even report it more frequently (e.g., monthly).

Arcane Research provides reports on this, for their clients. Here's their latest:

The selling pressure from the public bitcoin miners is easing #59239 https://arcane.no/research/the-selling-pressure-from-the-public-bitcoin-miners-is-easing

Not sure what you are saying there.