We're a small step right now from the police getting access to genetic databases like 23andMe, so if anyone in your family tree has gotten a genetic test it may be possible for them to identify you based on ancestry.
https://en.m.wikipedia.org/wiki/Joseph_James_DeAngelo#Invest...
Video by Veritassium about the case: https://m.youtube.com/watch?v=KT18KJouHWg
Based on the last 2 years of "show your papers" vaccine cards, I'm not sure why you'd pin this on Republicans.
Once they have a relative, it isn't that difficult to narrow it down to Bob. Think about it, you went from 350 million possible candidates to maybe 50 or less.
Go to the relative and ask them if they have any relatives in or near state X or city Y. That should narrow it down to a handful. And also you can narrow further by gender. Once you find a relative, you can logarithmically cull the search space.
Small correction, but an important one:
The ancestry portion of the consumer autosomal DNA testing does not imply genetic relation to another human being. By contrast, the genetic relative matching these tests perform is very accurate because it lines up matching SNPs between your test and others’ tests to determine relation.