Could the Imperium make waifu marines for coomers? Sure, Primaris opened that box of Pandora's.
Would it? It has no reason to in universe.
The entire premise would be:
A: You need females because there aren't enough males. However, the Imperium can easily sacrifice 10.000 men to create 1 space marine. Manpower is their biggest asset. So there is zero reason for the Imperium to do this in universe. They don't need to widen their recruit pool, they have all the manpower Stalin could ever dream of. Even if we say male and female recruits are totally equal, there is just so many men to throw at the Apothecary that you can already get any result you want through sheer brute-forcing of numbers.
B: Female marines would be super girly pin ups that trade strength for speed and agility. This would make a little more sense, but eldar are not that numerous to really deserve the massive undertaking that would make female marines into a new type of marine instead of twitter's butch muscle bound wet dreams. This would be even harder to pull off and require a lot of resources for an anti-eldar edge.
C: Female marines would be required to breed marines faster. Honshou already did it, and I don't think GW would dare that sjw screechstorm. This would only work if little marines grew up really fast and gave the Imperium an edge. This would again need a lot of resources, and the Imperium doesn't really need it that much, it thinks in centuries, reducing a marine's recruitment process to lets say 5 from 10 years wouldn't be that big a deal.
So... even if a bit of lore bending allows, there is no in-universe reason for the Imperium to actually bother with it. Even if we say a good space marine needs 10.000* male candidates to make, the whole Imperium's stock of 1 million marines would need 10 billion raw material as human men. So like, a few hive cities worth.
* Some Chapters like Grey Knights and Blood Ravens have such numbers, but for most 1.000 men would be more appropriate. That means 1 billion men. Earth today could produce that, there is 2.6 billion under 20 now. Half of that is 1.3, still above what the whole Imperium, a setting where Terra alone has QUADRILLIONS, would have access to.
And this scenario would be for repopulating ALL Chapters at once. Since a space marine has a battlefield life expectancy of around a century on the average... even real life Earth like planet could theoretically support the entire Astartes recruitment pool with much less effort.
The Imperium is the third powerhouse of manpower, with orks outdoing them and nids being the kings of numbers. But compared to something like the Federation or the Galactic Empire, their manpower reserves are still astounding. Even if we figure only a 3 kid per family unit birth rate (the 4th kid dies due to pollution, gang warfare, industrial accident, etc) they got this in the bag. And we are talking about a civilisation that propably has a fundie like approach to big families, so I'm once again low balling to be the C'tan's advocate.
They could easily have way more space marines if geneseed and gear was not a limiting factor.
Templin isn't even a 40k lore channel though. They are just a general normie "look at this sci-fi, than look at this one, than this one" scattershot generalist.
