When you have the Base64 string and you store it in any kind of storage then viewing it is as simple as retrieving the string and assigning it to an image component because it accepts Base64 directly to be the image to display.
This way, you store the Base64 in the table and you do not need to convert it to image again.
I made a quick demo for you.
See this project
https://x.thunkable.com/projectPage/61f68431c3761001dba12df1
In this demo it just reads the Base64 and assign it to an image and to a label but you can of course save it in any kind of database you wish to be retrieved later.
Sample result
