Heart Rate Monitor for Caveman?

I’m not tech savvy and not interested in gadgets like our current culture is obsessed with. But over the years I have benefited from using a heart rate monitor to track progress of conditioning and to properly do intervals. But one heart rate monitor broke a few years ago and before that another walked when I let someone borrow it at the gym.

Just curious if people here who are tech savvy and understand what products are out there, would have suggestions for an affordable and easy to use heart rate monitor? All I seem to understand is that one with a chest strap should be more accurate so I’d prefer that. However looking at prices they seem super expensive and I’m no Richie Rich. Anyone a guru on these? Ease of use for different HR zones during intervals, and perhaps if it monitors sleep too that could be nice to get data on.

Thanks for any suggestions or input.

https://www.ebay.co.uk/i/113384959176?chn=ps

I have one of these. They are very accurate. No need for a chest strap, will do HR zones (setp is via an app on your phone)
Monitors sleep (although I dont really use that)

All in all a good HRM if you can find it cheap enough.