instrument procedures (i.e. approaches) are published in text form,
and then rendered into NOS charts
1) Is this true?

Sort of. They aren't "published" exactly. The Flight Procedures
Office fills out several forms that describe the instrument
approaches.

If so, is this "raw" data available to the public somewhere?

Not really. They're on file at the regional Flight Procedures
Offices. They can let you look at copies, or they may even fax copies
to you. (I have several.)