Welcome to the community @earlyriser!
All Tidbyt apps that can be selected in the Tidbyt mobile app operate in the same way. Here’s how that works.
The app is executed on Tidbyt’s server, generating a very tiny 64x32 pixel WebP image/animation. That WebP file is pushed to the Tidbyt device that has the corresponding device ID and API key shown in the mobile app. The Tidbyt then displays that WebP image for that loop. The next time the app comes around in the loop, then the app will execute again on the server to send the new WebP file.
Considering the extremely small file size for a 64x32 WebP, it’s kind of a clever to just have the computation off device. Feels a little weird for something like a clock, but most of the apps being used rely on getting data from other online sources anyways.
The Tidbyt itself doesn’t really handle app logic.
Now, if you are running Pixlet render on your machine, that does basically the same thing — it runs the app code and generates a WebP file. Then when you do the API push it’s sending that WebP file to the device for that cycle. If you do the API push with an installation ID added in, then it will keep that WebP file cached and keep showing it in the app loop.