It's a pretty shitty spot but I think you can just jam given it's a 3-bet squeezed pot. He's still going to continue with stuff like QdQx or any other overpair with a diamond. Furthermore, you'd probably jam with stuff like AdKx or similar hands, so it's not like you just have the nuts here. You could also check/decide with stuff like KdKx/AdAx/etc.

Preflop both options are fine depending on your playstyle and table dynamics.

I'd bet more on the flop, especially at NL10 where you can expect static ranges and you don't have to have a consistent betsizing because few players will pay attention (and that's why you should be).

Turn is ugly. I feel like you're kinda priced in to go all the way for value, but vs. two players it's also super thin. I'd most likely go for a small bet/fold since I don't expect players at this limit to punish me for this highly exploitable line.

Dont like to 3bet pre. this hand doesnt play well OOP in 3 bets pots. Flop - bet bigger or c/r. c/r is good option here sine we will c/f this flop alot and can balance our check range with some strong hands and also we get all in on the flop.(good bc its so draw heavy)
On the turn with just over 1SPR we cant do anything else but bet calling. He doesnt have that many draws that he can bluff so I dont think we get that much value giving him the initiative.

Pre looks like a standard call to me. JJ is an ok squeeze with TT borderline depending on the other players but 99 isn't going to play well OOP in a reraised pot.

Flop texture is one where he's coming along or he isn't. Bet size won't make him change his range much, if at all, so make it much bigger, at least so we have a less than pot size bet left to shove on the turn.

As played we can't fold so I would just jam it in anyway.