PLO50 8775ds hero call river?

I think you might be overestimating the SDV of your hand. I like betting 50-66% otr for value straight/straight bluffs especially when you have the 8. Would villain fold kk-JJ here when facing a river bet? I agree, when he pots river it doesn't make a lot of sense, but he could have 66/22 FH.

A gutsy hero call on the river in PLO50 8775ds, demonstrating exceptional reading skills and confidence in one's hand. Bold moves like this can define a player's reputation at the table.

This one villain actually had QJ9x without any showdown value. Problem with call is that villain could have e.g. QJ98 type hand as bluff as well. Maybe some J99 though usually those should probably raise flop. Especially with nut wrap. So we potentially lose to top of bluffing range.

But yeah I would not expect to see trips either value betting (at least with pot bet) or bluffing. Overpairs should also have easy check. So interesting spot. There is definitely merit also in river bluff bet targeting less than trips to fold. If I did bet I would prefer half potting as that is sizing I would also use with straight if betting. We will also have some boats obviously but single sizing approach seems good to me in river as it then balances that with boats as well.

Would you have called, if he had bet 5,30 on the river?

Might have been less eager to call versus smaller bet.

MP RFI is fine imo. (over)folding still can make sense like if there is a lag otb.

The mid-high straight flops are terrible for us. You could simplify your strategy here towards checking full range ( I think you are the one who mentioned that once in this forum^^). If you still want to (bluff)cbet - very rarely- I think your hand is the best to do so (as its components straight-draw blockers, 2bdfd's, midpair and straight-draw each would improve the very low cbet freq slightly by 2-3%).

On the river I think it's a fold. You have plenty of better SDV to bluffcatch. I do pot bet here with this line in villains shoes as a default aswell, I don't think you can make any reads from his sizing after checking it twice oop, (like trips or underfull that checked back turn for potcontrol, if he is loose even worse since the straight is hard to hit and he could have catched up on such thing against opponents cbetting such flops too loose) and by itself does not tell much imo.