2020 brozz 250 looking to upgrade parts questions

[Brozz250]

My bike currently has 2112 miles on it and the chain shattered this morning locking up the rear tire. I'm look to upgrade the chain and sprockets

What is a good brand of chain and sprockets to look up and what it a better chain to sprocket ratio( if there is any to get more out of the bike)

What upgrades can I do to this bike to get more out of the brozz 250 (preferred brands upgrades to research)