You should not open hand this weak, clear fold PF.

fold pre, check back flop

Grunching.

Fold pre x2. These suits are too low, your cards are too disconnected, and you're in too early a position to VPIP either time. (Well, you have position on SB but after they 3bet you still have MP behind you... who makes kind of a strange fold imo.)

Flop: as played, check it back. Your fold is fine.

Your flop hand is way less decent than you suggest, but for that reason I honestly don't hate a bet/fold line in the abstract: you block dd a little bit and you block top two and middle set, but against a 3bet range from SB... blocking top two/middle set is kind of irrelevant as they shouldn't have a ton of 66 or K6 anyway.

So I like bet/fold in the abstract, but against a SB 3bet range it's slightly less reasonable, imo.

And because your diamonds are only ten-high, you just want to keep this pot small and realize your equity.

But to be super duper clear: you shouldn't have seen this flop in the first place. This combo should be folded until at least the CO.

Agree with what people are saying. Just want to add that at 2PLO rake is a huge consideration so should be playing much tighter than what is generally optimal.

Also my experience at these stakes is that most players only 3bet AA, so I like checking flop and trying to realize equity (turning two pair can stack a weak player overplaying AA)