The RPi should be able to handle your setup well. The MacMini likely gives you a better overall user experience, at the cost of a more costly and bulkier setup that requires mains power. For a long time my go-to solution was a Fitlet 2 mini computer, which is a great compromise between the two and which I like more than the RPi solution. But recently I went your suggested route and bought a 2018 MacMini, which is now my go-to system, with the Fitlet 2 as backup for anything more portable. So far I’ve used it down to -5 degrees Celsius and the heat produced by the computer was sufficient to keep it all warm enough to be working fine. I’m using
for it, which gives a nice bit of protection and I’m telling myself it keeps it a bit warmer. The 2020 M1 Mac mini is so energy efficient that it does not produce any heat at all, so would probably get colder over night. But since it is different electronics altogether, not sure if that means it can handle the cold better or worse.
If you connect from another Mac, you can simply use ‘Share screen’ from the finder, and if you connect from iPad/iPhone, you can use the free VNC viewer from RealVNC to connect. Mac’s come with an embedded VNC server installed.