I am under the impression that UTXOs indicate a higher number of Coins being hodled.
UTXO is unspent transaction output and that is exactly what it is, nothing more. the only thing we can conclude based on that is that adoption is growing. i don't think we can say by how much and that only works when you look at the set in a bigger interval like yearly not anything shorter.
This seems to be consistent with the great pump and subsequent collapse of 2017/18.
again it is "unspent transaction output", during 2017 bitcoin was under a sever spam attack. one form of spam attack is to increase the size of UTXO set as the attacker creates thousands of transactions every second and that causes the spike.
it has nothing to do with the price.
However, since the beginning of 2019, UTXO has been skyrocketing continually with no sign of slowing. Does this indicate more holders? Do you take this to be a positive?
it is only "holders" if those outputs aren't spent for long time such as years. and unless you find a way to analyze that you can not make that conclusion.
as i said that increase mostly shows adoption, and that is a positive thing.