is there a pin-pin replacement for STM8L151K6U. These Micro's are back ordered for 2023 delivery.

[Tesla DeLorean]

Seriously consider just doing a clean-sheet redesign with parts you can source and inventory.

I don't see the current situation improving within the next 12 months.

[Thomas G]

Did you try sourcing STM8L152K6U?

A mild PCB re-design that accepts other STM8L variants might be the 2nd best option. I know of other people in the same situation and it's doubtful that it will change in the next two years. I know of small-scale products that now take a lateral approach - use whatever is available and make the product design really flexible. Yes, that's expensive.