To truly understand and replicate pregnancy in men, huge amounts of research to study pregnancy in women would need to be done.
Now, maybe this would provide the source of funding for that type of research which is currently considered a low priority and not worth which might suddenly appear because its now men pursuing it.
I do think in time that the science will be developed because its a holy grail for a scientist but when that happens is related to demand and money behind it.
But that still comes back to the point that why would anyone want to put their body through that much trauma if they didn't have to? Maybe for the kudos of being 'the first' as some sort of trophy. But the fact it will always require heavy duty medical intervention makes it much more attractive to get someone else to do it for you, but to change the language around how you are somehow pregnant if someone else is doing it for you (watch out for pseudo science of surrogates having bonds to their carrier and having symptoms in sympathy).
For the money to follow, there has to be a power and a status attached to being pregnant that there currently isn't, for it to become widespread and to initiate the science needed.
And even if the ability to become pregnant is developed, it still will rely on the harvesting of eggs from somewhere. They won't just magically appear from nowhere. The technology to self clone or man made eggs, is much further into the future than the 'transwomen can be pregnant' crowd are suggesting.
If its about control of the production of children, then there is another more sinister source of money that could come into play of course. If that is, indeed the case, then this is very much also about the control of women and not merely about men believing they are women and having the best interests of women at heart. There is a rotten selfishness at its core, with little regard for others.