any advice
Not really, but I do have some thoughts you might want to consider.
If he's on these apps, it's likely that either he's either happy with you and is trying to have his cake and eat it by continuing to shag other women, or, he's really unhappy.
If he was there to just browse, he wouldn't have any photos uploaded. He's uploaded a photo of himself so that women can get a good look at him, decide to swipe on him and start chatting which I'm sure which would lead to sexting at the very minimum, with a good possibility of sex.
I'm sorry OP, but I don't think most men who were genuinely content, mature, sexually satisfied and ready for fatherhood would do this. It's usually the action of an immature pleb who is having a panic about fatherhood and his youth slipping away from him. Is he planning plenty of lads weekends away as well for when the baby's born, or lot of late nights working so he can avoid as much baby care as he can?
I note that he's your boyfriend, not your husband. Do you want to get married? Have you talked about marriage? Was the baby planned? How long have you been together?
I'd be surprised if he turns out to be a motivated, hands-on Dad. Decent men don't cheat or go looking around especially when their partners are pregnant.