I don't think he will be a good fit for X-MEN at all, anymore than he will be a good fit for a Batman film. he seems to know a particular style of comic films, although with SS2, he comes off much happier because he got more freedom.
X-Force is a film I have been thinking about because marvel and DC do have some kind repour with each other.
There would be no Captain America Civil War if there was no Batman vs Superman and there would have been no captain marvel if there was no wonder woman and no doubt spiderman no way home and the flash movie were made to respond to eachother.
However marvel now I think have reached an end with the repour on this one. they just will not be able to respond to SS 2 even if x-force would have been a good answer but you need to make X-Force an R film and also find a way to tone down the comedy and humor even if Deadpool is in the movie, which is something Gunn does not know how to do but even if there is no Gunn on X-Force, Marvel just cannot make any more R film apart from Deadpool 3. Something Gunn seem to have used well in SS2 (The R Rating)