I can’t quite figure out if what you said here indicate you are aware of this or not, but Orca actually has exactly this setting in the filament profiles. If you measure 99.92 mm for a 100.00 mm test, you’d set it to 99.92 - simple as that.
On a random note I’ve had the idea to print two test lines/walls, high enough for a good caliper reading, 150 mm apart (actually if they are 0.42 mm wide they’d be 149.16 mm apart) or rather four of them, one set for X and one for Y, and then measure after cooling but while they’re still adhered to the build plate (using the Cool plate would probably be a good idea). This should mostly show the printer’s own error rather than shrinkage. It might be nice to correct that with M290.2, and only then measure filament shrinkage and compensate for it with the mentioned Orca setting.
[Edit: Corrected M292.2 to M290.2, typo in original thread]