WordPress-Plugin-Boilerplate VS underpin

I just started on a new plugin, and I used this boilerplate as my jumping-off point. So far, it seems to abstract away from wordpress just a little less than something like the Underpin framework I linked to in the original post does, so I feel like it's helping me get a bit of a feel for how WP handles things, while also adding some much-needed structure and doing things like helping separate the dashboard side from the frontend side. As for the REST API side, where would you turn to that? Is that just when you want to expose bits of the site to external services, or would you use it to allow internal components to communicate with one another or something like that?

https://pippinsplugins.com/learn/. I learned quite a bit from Pippin. I use the WordPress Plugin Boilerplate when I create custom plugins (https://wppb.io/). If you go that route, you'll end up learning OOP PHP in the process.

The WordPress Plugin Boilerplate is a nice template for starting your next plugin. It's certainly not the only way to do things, but you can learn a lot by going through it.

Take a look at the plugin boilerplate repo to get an idea of how a good plugin (with more than just basic functionality) might be set up. Way down at the bottom of plugin-name.php, it calls run_plugin_name(), which then calls other things and other things and other things, etc.

I recently came across mention of the Underpin WP framework, and was initially very enthused with what it could do, and I realized how much I needed something like that. I tried to get into it, but realized that since its latest update the docs have been sorely lacking, and I haven't been able to get much to work with it. As a result, I probably wouldn't want to lean on it too much anyway, even if I could get it to work.