I honestly believe that gas would be less but still high by historical standards. The inflation was coming no matter who was President but it would have been slightly less under Trump. Trump was good for the economy until COVID hit.
Trump would have handled the Afghanistan withdrawal better. He wouldn't have moved as quickly to withdraw and would have placed less faith in the Afghan army. He's non trusting of foreigners by his nature.
That said....
He would have handled Ukraine horribly. He is way, way too cozy with Putin. He has intirely too much respect for dictators because of his own personality traits.
His isolationist tendencies also would have led to appeasement and a lack of cohesion with NATO. He would have pissed off our allies as he bragged about how he was right about them needing to spend more on defense. He would have said Ukraine is none of our business and put minimal effort into arms or support for Ukraine. His policies would have helped make Russia stronger than ever which is a huge danger to Europe and the world including America.
Trump is an idiot savant. Highly intelligent in some areas like business and $$$ but dumber than owl shit about big picture social/geo political issues like our democracy, ethics/morals and the US role as the world leader.
For all Biden's flaws....he is much better suited for dealing with Putin and Ukraine than Trump.