I've also tried infinite2x before but it wasn't working properly, was basically unusable for me. Now it seems it's gone from the AppStore completely. If you know any other alternatives, do let me know.
Judging by the power the Macbook Neo has with only an iPhone chip this made me wonder why can't we have something like Samsung DeX on iPhone. This app (External Display Browser) seems the best close enough thing to DeX we'll get given Apple's limitations. Hopefully now with the iPhone Fold, Apple will decide to offer better support for bigger external screens and maybe something that can rival what Android already has (DeX and Android Desktop Mode)