Get bigger tyres/move to tubeless and drop the pressures will probably be a cheaper/easier way to go.
If it's your arse you're worried about get a Suntour SP12 and Selle seat
Carbon forks and bars can make a big comfort difference, did on my old fatbike (On One Fatty Carbon fork and On One Knuckleball bars). Grips can help too, I fitted some On One foam grips, better than the default solid rubber offerings.
Recently fitted a set of 38mm Prime Primavera Carbon bars to my road bike and they are so comfy, even without tape.
If it's your arse you're worried about get a Suntour SP12
I think the post I've got is too big for you too anyway. It's 35mm...
My hybrid is 27.2 and MTB is 31.6
I'm happy to swap if you are. Otherwise I'll return it. Shame as I found it quite cheap but they only have 31.6 in stock.