The fact that Geralt has a penis is not enough to make me forget that he is not me. Throughout the series, you’re constantly learning stuff about a character that isn’t you, that you aren’t writing. I doubt they have examined their feelings.
They probably project themselves over the character and feel like they’re really the one getting the rewards.
The thing that always got rid of immersion for me as I ride my noble steed across the countryside to defeat mythical monsters from a mythology not my own was (1) geralt sounds too much like Gerald (2) his magic is trash/boring and (3) his crossbow is weak af. Never had a lot of difficulties with whether he had a dick or not.