The phrase "resounding thumbs" means a very loud and clear sound made by thumbs, often heard when someone strongly agrees with or supports something. Full definition
An outside panel of experts gave a resounding thumbs up to GW Pharmaceuticals» cannabis - based experimental treatment for rare, childhood epilepsy and seizure disorders. (fortune.com)
The cupcakes got a resounding thumbs up from the taste testers, particularly one who had just come home from a long day at work and devoured two of these cupcakes in one sitting! (whatjessicabakednext.com)
And if you were wondering, they got a resounding thumbs up from the people who tasted the originals. (chefambershea.com)