I’m loathed to drill out the front mech lugs in case I ever have the need for one again but I was wondering if it’s possible to run a dropper post cable through the front mech lugs and have the cable outer split, just like a front mech is? Would it work still? I think it will but what if I ever need to remove the post, will I have to undo the cable at the clamp to provide the give so I can pull the outer back a few mm to release the cable?

Yes it will work fine as long as there are no snags in the routing, but you can also buy convertors that allow you to run full outers on cable stops.

You shoudl be able to remove the post by just pulling on the housing – the cable has to be able to move enough to actualte the post, so assumedly it can move enough to free up the outer from a lug.

I’ve run a Gravity Dropper like this (my Blur came with a set of “lugs” specifically for a dropper).

You’re right, with no length adjustment possible you’d have to detach the cable from the lever or seatpost.

I didn’t try it but perhaps an inline cable adjuster would provide enough slack? Just wind it all the way out when fitting and setup, then wind it back in when you want to remove the dropper.