The new set of data container widgets (Datagrid2, Gallery, etc.) don’t work with existing third party marketplace search widgets. However, they have a new out of the box search function built into them.
In their properties they have a ‘Filtering’ tab. There you can enable filtering and set the searchable attributes. Then you will need to place relevant filtering widgets(matched to the searchable attributes data type) in the header area of the Gallery.
There are more details in the documentation here: https://docs.mendix.com/appstore/modules/gallery/#3-filtering
Hope this helps