Maybe 😀
A few times recently, literally freezing outside, ice on the ground, mud frozen to the bike, but the Garmin says +10C but yeah I guess the bag is insulated.
To be fair I don’t carry the spare seatpost with me (though is in the car) 😀
I have occasionally run it on the bars if I’m out myself on a longer ride just for interest, though without maps I don’t really pay any attention to the data while riding. I haven’t tried using it to follow a route yet. I know it would be breadcrumb trails rather than a map on the 510. Been reluctant due to reports of people losing rides when they’ve followed routes.
Might give it a go tonight on the bars and see what the temperature says.