This is exactly what I’ve been doing in a BASH-script.
One GREP-command fixes the job of finding all the files with a given (Regular) Expression, which I put in a processing file (for safety reasons only and tracability).
The SED-command fixes the job of putting the expression between [[]] for all the files in the processing file.
Then I transform the processing files into a MOC with links to the processed files.
Would be a nice feature within Obsidian only thing for me is speed.
This scripts takes me max. 10 seconds to process 180K files all-in.
Don’t know if that is do-able in Obsidian