Is this bike any good for 8yo?

Hi all, There is this bike on sale right now which looks like exactly something that my son would love. https://www.millets.co.uk/16600971/polygon-relic-20-kids-bike-16600971 is this any good?

He is 8yo 124cm (on a smaller size, slim and athletic).

From online articles etc he is between sizes 20" and 24" but considering he is on a smaller size I thought 20" would suit him well. We tried this one https://www.decathlon.co.uk/p/kids-20-hybrid-bike-riverside-900-6-9-years/_/R-p-313214?mc=8576531&c=grey%20green in the shop and it seemed to fit him well.

Thank you for any advice