[FREE] Shimmer View - An extension for applying shimmer effect on any view component wit many customizations

Extensions
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22

from the extensions directory App Inventor Extensions | Pura Vida Apps

Shimmer Layout Extension by Aarush_Kumar
Shimmer TextView Extension by Sumit1334
Shimmer View Extension by Sumit1334

you might want to try something and if you get issues, post a screenshot of your relevant blocks

Taifun