@ExTechOp here is an old instruction with most of it obsolete, but I think that you need what is listed under “Install software” here. I believe these are the packages that your search with “microg” finds for you.
The signature spoofing should happen on the house nowadays. I don’t think you need to do much else than to start with microG Services Core and see to it that you get all the ticks in place in the Self-check.