If the match proceeds to penalties, then PSG might comfortably win it; that was how Chelsea won it in the same venue against Bayern Munich in the 2012/13 season.
PSG have a very good goalkeeper, the keeper Donnaroma has been saving them in the Champions League this season even against arsenal in both legs, he will be a key player in the final because Lautaro Martinez will surely find his way to make attempt despite PSG’s defense, while Donnaruma will make effort to defend the goals.
I am considering Inter Milan in this final as well since they lost to Manchester City two seasons ago, and they have already did well to eliminate Barcelona; therefore, since they lost their league title to Napoli, they will do their best to win the Champions League this season.
Penalty is a game of luck and we can't say this is the team to win it, even the best in the world of football do miss penalty and I'd say is luck that Chelsea won the game that year, penalty is anybody's game. Another thing is that PSG have a good goalkeeper which you mentioned but their defenders are not even strong enough to withstand the pressure of Inter Milan's attackers.
I agree with you, Inter will never let this only opportunity slide and same as PSG but since they (PSG) won the Ligue 1 title I some how feel that they are going to lose this one. Inter have nothing this season while PSG have their league and their FA Cup or whatever is called, so that alone will make Inter fight more than they did against Barcelona to win this title and we shouldn't hope on it to end on penalty.