There has been strong demands and voice from my end user of the app to introduce this feature, upload bulk number of image file to appsheet at once.
There is no native feature for the moment to achieve this.
To make it happen, i created the external service web app. To interact with Appsheet app, this custom app is driven basically by Appsheet API, FIND, POST methods.
Apart from that, i used Google Firebase/FIrestore to store the image file and path to the url for image file, which is then copied to data source where Appsheet app lives on.
It is working fine.