My wife’s grandmother was unmarried when my wife’s mother was born. No father is listed on the birth certificate, but there was generally accepted family folklore as to who the father was. Ancestry DNA testing entirely blew up that theory! We now have no idea who the mystery grandfather is.
There are more things to consider in choosing a test. Do a bit of reading. At the very least read a few reviews. This is a bit out of date but will help. (Price info is very out of date. There are Father’s Day sales right now.) https://isogg.org/wiki/Autosomal_DNA_testing_comparison_chart Personally, I think Ancestry is the WORST of the major companies, but that’s just my personal opinion.