A lot of boomer shooters nowadays have a female protagonist, e.g. Selaco[0], Supplice[1], The Citadel[2] and its sequel[3], Zortch[4] (and its upcoming sequel[5]), Nighmare Reaper[6], COVEN[7], Viscerafest[8], Hedon[9], etc. If anything i'd say that nowadays there are way more boomer shooters with female protagonists than not :-P (combining the tags "boomer shooter" with "female protagonist" on Steam search gives 143 results, though that includes games where you can either choose your character's gender or you play as a woman for a part of the game even if you play as a man for most of it).
[0] https://store.steampowered.com/app/1592280/Selaco/
[1] https://store.steampowered.com/app/1693280/Supplice/
[2] https://store.steampowered.com/app/1378290/The_Citadel/
[3] https://store.steampowered.com/app/3371240/Beyond_Citadel/
[4] https://store.steampowered.com/app/2443360/Zortch/
[5] https://store.steampowered.com/app/3807500/Zortch_2/
[6] https://store.steampowered.com/app/1051690/Nightmare_Reaper/
[7] https://store.steampowered.com/app/1785940/COVEN/
[8] https://store.steampowered.com/app/1406780/Viscerafest/
[9] https://store.steampowered.com/app/1072150/Hedon_Bloodrite/
143 results means it's relatively rare.