Came to recommend Synology; I've worked on small systems (4 cameras) and large (30+ cameras). For home use you can probably get away with their smallest NAS which includes free CCTV software (Surveillance Station) which itself includes 2 camera licenses. Adding more cameras beyond those will require a one-time license purchase. While this is not the cheapest route they are easy to setup, manage and use.
ProtonVPN works great via Wiregurd on Linux as well just not through the GUI; you can download the configs and connect through terminal or other Wireguard client
Came to recommend Synology; I've worked on small systems (4 cameras) and large (30+ cameras). For home use you can probably get away with their smallest NAS which includes free CCTV software (Surveillance Station) which itself includes 2 camera licenses. Adding more cameras beyond those will require a one-time license purchase. While this is not the cheapest route they are easy to setup, manage and use.