Is there a way to track the indexing status?
To know if a file is indexed look at the
contentHints.indexableText property by using the get method from Google Drive REST API.
Is there a way to force a specific folder on Drive to be indexed with priority?
AFAIK Google Drive doesn't include any way for end users to force a specific folder to be indexed with priority.
It's worth to say that on contrary of other filesystems, in Google Drive folders are not related to the physical location of files on Google's servers, they are just a way to help users to organize files in a way that is comprehensible by most of them.
Saving indexable text
Drive automatically indexes documents for search when it recognizes
the file type. This includes text documents, PDFs, images with text,
and other common types. If your app saves other types of files
(drawings, video, shortcuts), you can improve the discoverability by
supplying indexable text.
Indexable text is indexed as HTML. If you save the indexable text
string Here's some text, then
"Here's some text" is indexed, but "value1" is not. Because of this,
saving XML as indexable text isn't as useful as saving HTML. Also keep
The size limit for contentHints.indexableText is 128K. Don't try to
sort text in order of importance; the indexer does that very
efficiently for you. Indexable text should be updated by your
application with each save. Make sure the text is related to the
content of the file. This last point may seem obvious, but it is quite
important. It's not a good idea to add commonly searched terms to try
and force a file to show up in search results. This can frustrate
users, and might even motivate them to delete the file.