I’ve never used one but for small and cheap (used sell for < £40-50 on eBay) there is the Garmin 25. Won’t ever support Power, has a small screen and unsure how slick the sync features are.
As someone who looks at their bike computer all the time, maybe best to start with a device that is all about looking back/strava, etc… and focus more on the riding and adventures while on the bike.