I also feel overwhelmed with HA homelab stuff.

HA on my RPI is just not reliable, requiring a reboot 4-6 times a year for reasons I don't understand. Frustration at being in the literal dark doesn't translate to the right mindset to root cause.

What I need is an opinionated guide on minimum viable virtualization, but so much of the resources online are from folks that are homelabing maximalists.

I feel the same temptation as parent to create a spartan solution.

You're making it complicated with all the VLANs. HAOS in a VM (proxmox helper scripts for one-line install), and HA has plugins for all the other things.

Just deny WAN access to the IoT junk you don't trust at the router, or for things like cameras, a separate switch for those. That usually makes sense, since they're one of the few devices that must be powered with PoE and doesn't require gig+ bandwidth. A cheap 100mbit PoE switch will handle a good number of cameras.

This - the move is to grab some zigbee smart plugs. Once you have HA up and running there are so many applications for these.

I have a door sensor that monitors my kids bedroom door, and when it opens it turns on a desk lamp in my room. This allows me to get to him before he gets to my partner who's sleeping with the new born.

Pretty much all mains powered Zigbee devices also act as routers in the mesh.

I dabbled in hydroponics for some years. Due to my inability to get my Rasberry Pi and Arduino working I ended up using a 12V pump and one of those cheap $10 electric timers on Aliexpress. I estimated how much time it took for my hydroponics system to drain and that's what I set on the timer. Other people I followed had all sorts of sensors rigged up, which I would have done if I had the time and skill but I failed, so in the end it was just the timer. I too had single solar panel and battery and the system worked for over 7 years with no issues. I just replaced the pump once or twice.

An art student of mine once needed a way to electrically control precise small amounts of water. We solved that using:

  1. Water tank and gravity  
  
  2. Medical IV flow regulator¹  
  
  3. Servo hooked up to that IV flow regulator via a 3D-printed part  
  

¹: see https://www.gvs.com/en/catalog/iv-flow-regulators

HA is essentially a better cron. It unsurprisingly uses the cron syntax where appropriate.

I used to run HA on an RPi, but eventually migrated it to a similar NUC. The RPi eventually just wasn't powerful enough (peak compute needs), while the NUCs are still quite cheap. And you can run a surprising amount of Proxmox VMs and LXCs on barely a few cores and gigabytes of RAM.