Every house has one — the iPad that got replaced when a newer model came out and now lives in a drawer or propped against the fruit bowl. It still works fine. The battery holds a charge. The screen is perfectly good. It just isn't fast enough to be your daily driver anymore. That's not a problem; that's a dashboard waiting to happen.
The setup: plug it in permanently (yes, always plugged in — the battery will degrade slightly over years but it doesn't matter for a fixed display), put it in a wall mount or a stand at counter height, and lock it into a single app using Guided Access. On iOS, Guided Access is in Settings → Accessibility → Guided Access. Enable it, open the app you want, triple-click the side button, and it never leaves that app. No accidental swipes to the home screen.
The app: Notion for a family dashboard, Google Calendar if everyone's on Google, or Home Assistant Companion if you're running a homelab. Home Assistant is the best option if you want weather, calendar, smart home controls, and who's home all on one screen. The Companion app is free and works beautifully as a full-screen dashboard with a little configuration.
If you're not in the Home Assistant world, a simpler option is Mango 5Star or Dakboard (free tier is fine). Both are designed specifically for this use case and take about 20 minutes to set up. Point them at a Google Calendar, add a weather widget, and you're done.
One tip that makes a real difference: enable Night Shift and set it to run all day at full warmth, then reduce screen brightness to about 30%. At night it's not blinding, during the day it's still readable. If you want to go further, Adaptive Lighting in Home Assistant can dim the screen automatically from sunset to sunrise.