Mac mini won't consume too much electricity, its processor is ARM based. It'll probably cost few cents a day to run.

with hetzner, the closest comparable option (16gb ram, 8 core ampere cpu) with a base model mac mini will annually cost almost 50% of the mac mini price. so cost wise, mac mini is equal to 2 years of hetzner vm. (comparing prices as of today for both, earlier mac mini used to be quite cheap).

I already have residential internet. The only downside is having to ensure uninterrupted power and internet. and also the friction of connecting remotely via ssh.