I’m in the exact same boat.
You cannot just swap the top cap to the lever type as the damper assembly is different – the lockout version ‘springs’ back to open, thus it needs the cable tension from the lockout to hold it closed. They ‘fail’ open.
The lever versions are unsprung and thus remain at whatever position you leave it at.
You can see the differences in the tech manual that the damper has a unique p/n.
My fork is from Scott so would have had the Scott twinloc handlebar cavle explosion thing going on.
I’ve been hovering over one of these for ages:
https://www.trekbikes.com/gb/en_GB/equipment/cycling-components/bike-seatposts-accessories/bike-seatpost-parts-and-accessories/bontrager-droplock-remote/p/33107/
Which would replace my existing dropper lever too. But I’m not £100 annoyed by it being missing yet!