Simply use https://botsgg.snazzah.dev/widget/<client_id>/default.svg as an image URL and it will generate a nice widget.
Currently there are two widget types: default and banner as shown above. You can replace the end of the url with <type>.svg to change it.
You can change the width of the widget using w in a query string. (ex. ?w=500 for 500 pixels)
You can also use badges with https://botsgg.snazzah.dev/badge/<client_id>/servers. The available badge types are servers, library, and status. You can use the query parameters as listed in the Shields.io documentation except logo, url, cacheSeconds, and link.