Mining Bitcoin? Unlikely since only pool know your IP.
Running Bitcoin node? More likely since your IP will be known to other node and appear on crawler website such as
https://bitnodes.io/.
Never mind this newbie-like question. Some people's location are unknown, are they those that uses Tor or VPN? If using Tor or VPN, you can set it to a country address, the country the Tor or VPN is set to will be displayed as the country set to? This later is how I thought it would be, but how come some location are unknown?
When a node use Tor, usually it means they only use
.onion address (doesn't use exit node) which prevent Bitnodes.io from guessing their country. And if those who run node with Tor for privacy reason, usually they don't configure their node to accept clearnet connection.