Multiple Apps on Pi4

Does anybody have any recommendations for using 2 apps on the same Pi4 like PiVPN and Nextcloud, would there be any issues with performance or do you recommend using multiple Pi4’s to accomplish this?

One Pi easily enough. Install them, run htop from the commandline - you’ll see you have plenty of resources left.

if you are using a RPi4 4GB, you will have so much resources free, you even don’t know what to do with it. We have seen people having installed 7 or 8 apps, using smaller devices than RPi4.