Looking for a dropper post with layback, ideally 27.2, but currently use a shim and could go slightly bigger.

What can you recommend?

A better-fitting frame.

It’s not difficult to see why a layback/setback dropper post is a bad idea from an engineering viewpoint.

KS eTEN has layback and comes in 27.2.
100mm drop only, there is a 125mm version but I think you’d need the shim.

I got mine from here: https://www.bike-discount.de/en/search?q=eten
£85 a few years ago 😉
It was great and is easy to service but eventually died after just over 2 years.

The older Specialized Command droppers have a layback too if you can find one for sale. Not sure if they’re available in 27.2mm though?