- How do i get Data from the DB to the frontend (vue.js)? Can i use the REST API for the WPDB?
The REST API works for this, or you could include the data in the HTML as JSON or a window variable
- How can i use a custom post type to “feed” information into my widget? I assume i can just get the data from the WPDB about my custom post (storing the settings as part of the custom post), but that just brings me back to the first question.
The REST API, this is pretty much the same question as above. Note that fetching posts in WP via WPDB is highly unusual, and is commonly considered a code smell and bad practice. WP_Query is a far superior/easier method
- Do i use a “post template” to “inject” my widget, or is there something else for that?
You could do that, but it would be easier to build a block or shortcode
Keep in mind, that retrieving the data and putting/embedding something in a post are on topic, but Vue.js is offtopic, you’ll need to consult Vue.js communities on how it’s used.