If you’d rather keep Vikunja as the backend and web UI, it has a CalDAV endpoint, so you can point DAVx5 at it and use Tasks.org or jtx Board on Android for the reminders themselves. That gets you native Android notifications without email, and you keep the web interface for planning. Vikunja’s CalDAV side is less mature than its web UI, though, so test whether due dates and reminders come across the way you expect before moving everything over.

For notifications that aren’t tied to a task app (say, “remind me when X happens” from a script or Home Assistant), ntfy is the simplest self-hosted push to Android, as mentioned above.

The most useful number you can get is from your own stack: put your actual app on the box and hit it with k6 or wrk using a realistic mix of pages, and watch memory rather than CPU. On 2 GB the failure mode is almost always RAM: too many PHP-FPM/worker processes plus a database on default buffers, then swap thrashing and the OOM killer, long before the single core is the limit.

What buys the most headroom on boxes this size:

• cap the worker count (pm.max_children or the equivalent) to what actually fits in RAM
• size the DB buffer pool deliberately instead of leaving defaults
• zram for bursts
• serve anything static or cacheable straight from nginx so it never touches the app

And rate-limit or block the obvious scrapers. As someone said above, bot traffic is often the real load.

If you end up running it headless (game streaming host, Jellyfin/Immich worker, whatever), two small things save a lot of hassle:

• Get an HDMI dummy plug (a “display emulator”, a few euros). With no internal panel detected and nothing on HDMI, the GPU often has no proper display to render to, and Sunshine/Steam streaming in particular wants a “real” display to capture at the resolution you pick.
• Check the BIOS for a “power on after AC loss” / “auto power on” option. Plenty of laptops don’t have it, but if yours does, it comes back on its own after an outage like a proper server. Otherwise Wake-on-LAN from one of your mini PCs is the fallback.

And since storage is your bottleneck right now, open it up and see if there’s a second M.2 slot. Some of these chassis have one, and then it could hold some data while also taking the Immich/Paperless ML jobs on the 3050Ti.

Nice, this is one of those automations that pays for itself the first winter. Two small things that might make it nicer to live with:

The loop with the namespace can be a one-liner, and you can limit it to the next couple of days so a cold snap six days out doesn’t nag you every morning all week:

{{ (daily['weather.forecast_home'].forecast[:2]
    | map(attribute='templow') | min) < minTemp }}

And to stop repeat alerts once you’ve actually done the work, pair it with an input_boolean like outdoor_water_winterized: add it as a condition (only notify when off), send the notification with an actionable button (“Done”) from the companion app, and have the button event flip the boolean on. Then a second automation turns it back off when the forecast lows climb above, say, 8 °C for a few days in spring. That also covers curbstickle’s point if you ever add more taps, one boolean per tap.