Experienced self-hoster, novice home-automator. Looking to deploy my very first home security system and I have no idea what to pick

My girlfriend just bought her first house, and is looking to set up a security system for it. As the resident techie, I've been tasked with looking into researching and deploying a setup. I know these posts are pretty common but none of the options I've come across so far look particularity attractive.

Eventually, my goal is to build a homeserver/NAS for my GF to keep at her house, which could manage many home-automation things, which I naturally assumed would include the security system. I initially thought I would have more time to plan out a system, but she wants it deployed ASAP.

The way I see it, there are two routes I can take. The "all in one" setups which are plug and play, but seem quite limited, or a totally DIY solution.

The fully DIY solution seems more attractive to me, because

  • Sounds fun
  • Can more easily integrate with other solutions (home assistant, etc)
  • Easily upgradeable in the future (new cameras, drives, etc)

but

  • I would be the only one knowledgeable enough to configure/maintain it
  • Would take longer to research and deploy

As for the "all in one"

  • easy setup
  • no confusion about compatible cameras and software
  • GF can maintain and upgrade herself

but

  • vendor lock-in
  • random annoyances
    • Synology Security requires licenses if you have > 2 cameras
    • Blue Iris is Windows Only
  • expensive upgrade paths
  • redundant hardware (she still wants a homeserver eventually)

Here are a breakdown of requirements, questions, and considerations

  • Two story home with backyard, front yard, and garage. Will need at least three cameras to start
    • What cameras are best?
      • Can they all use PoE? or is WiFi better?
      • Cameras without vendor lock in required
      • Weatherproofing?
  • Best Video Management Software (VMS)
    • Seems like a lot of limitations!
      • Blue Iris is Windows only :face_vomiting:
      • Synology Security has license fees
    • I want something modular and open!

As for the server hardware itself, I can handle that easily. I can throw Linux on a tower with handful of drives. My area of confusion is everything else, basically the cameras and other associated hardware. Do I need a network switch? How do I power them?

Thanks