Most of mine are just using little wall-warts through micro-USB cables. The star-tracking camera mount (which I even lugged up a little foothill for the eclipse

Most of mine are just using little wall-warts through micro-USB cables. The star-tracking camera mount (which I even lugged up a little foothill for the eclipse), is battery powered, usually using one of those USB battery packs designed to charge phones. I can also hook it to my deep cycle battery when I'm camping or whatever through a small 12V -> 5V circuit (it's used for other things too). ESPs do have super low power modes for things like the door sensors that only need to do anything when they're triggered an for those you can power them with lithium batteries for pretty long times.