We have quite quickly become a chromebook family, from 6yo kids to their great-grand-parents. They are so simple to use, but feel like proper computers, not toys like ipads.
Neverware is a good concept, BUT it doesn't have android app support (and isn't going to in the near future). I love our touchscreen chromebooks with fold-back screens that can be android tablets as well; without access to the play store the chromeos platform is seriously impoverished IMO, so I wouldn't consider NeverWare myself. We play lots of android board games on them en famille! But they get serious use for school and work as well.
You can easily plug external screens and peripherals into chromebooks, though obv it depends on the ports you've got, The latest generation of chromebooks don't have hdmi for some reason so you might need a USB-C adaptor for a tellly (£10ish).
The ChromeOS expiry date thing is a real time-bomb that almost no-one knows about - even the people working in a well-known high street retailer couldn't tell me when each model expired!! I saw a Chromebook that was going to expire in 18 months on sale for £400! The link you need is this, it tells you all the expiry dates for the various models: support.google.com/chrome/a/answer/6220366?hl=en
Shame on google for not making this information easier to find.
I don't know what your budget or preferences are, but we got this for our 6yo - good till June 2025, ruggedised, splash-proof, 1.3kg, 11.6' touch-screen and £280 - www.ebuyer.com/874317-lenovo-300e-chromebook-2nd-gen-mtk-81qc0004uk. Upgrade to the 500e (£400) gets you 64Gb storage, a stylus and a second camera. I thought the lack of 1080p screen would be a deal-breaker for me but actually I use it loads when he's gone to bed!
HTH