Shopify has really strict guidelines and review processing for official themes. If you can get accepted it's probably lucrative but I wouldn't put most my eggs

Shopify has really strict guidelines and review processing for official themes. If you can get accepted it's probably lucrative but I wouldn't put most my eggs in that basket. Whether or not you're accepted seems to be somewhat arbitrary or at least too subjective. You can release a theme on themeforest without all the hubub, but you're competing with a lot of developers, and there's tons of mediocre stuff so you'll have to stand out in some way.