Shopify is the best eCommerce platform I’ve ever encountered. It’s very to set-up shop and has a lot of features to get you started. There are tons of apps to meet whatever your shop needs. However, just like WordPress plugins, it can jack up the overall cost, so be wary and use only the ones that are really needed. As a web developer, one of my favorite is the free Advanced Custom Fields, very useful for customizations. The online shop comes with a blogging features and email marketing, but limited.
To spare you the trouble, take advantage of dropshipping. They have an extensive post about it here. Personally, I like Spocket, they source products from the US and EU. Don’t ruin your business by selling cheap but low-quality products.
In this time of the pandemic, they have offered pause plans, which is a big help for owners. One of my clients is an event organizer that hosts seasonal events, so the Pause and Pause and Build plans come in handy for them. The Pause plan completely pauses your online site, including any admin works for 3 months at zero cost. After which it is automatically upgraded to Pause and Build which charges just $9/month. In this plan, the online store is still not available, but you can do backend admin tasks.
Shopify also offers POS, both as a mobile app and in-store terminal.
As a web developer, I also create custom-built apps for clients. To do so, register a Shopify Partner account. It comes with a free online shop you can experiment on. It’s not live of course.
The easiest way to create an app is to use an Ajax call to an external service hosting the files that process these requests. To prevent any cross-domain issues, use the built-in Application Proxy App extension. Here a cheat sheet and Liquid examples.
For any problem that’s difficult to resolve, contact Shopify Support, they’re friendy.