Neville, definitely! We’re talking about people who are mentally ill and liable to kill themselves if their fantasies aren’t indulged. Issurim of lo yilbash, mesares, etc, are chamur, but not yehereg velo yaavor, so the poskim allow it for pikuach nefesh.
The dor tahapuchos, which was kept under the radar for many years and was used only by rabbonim who were asked such shailos back when society was a bit more sane, is now available to the public. It was reviewed by an odom gadol, i just forgot which one. You can find it online, too.
His chidush about shul and other social situations is that others will look at him as a woman, and That’s taaruvos.
But for these people it’s usually not about doing teshuvah so much as getting psychiatric help. If they’re cured of their illness and want to go back to being their real gender, then of course they should; no one’s going to argue with that.
And I’m sure many do it b’issur because society tells them that it’s ok and they’re just ready to be oiver; for him, he needs to do teshuva, obviously.