Lawnchair, according to the devs, is not abandoned. In late November (of 2023), they said:
Sorry for the long break in Lawnchair announcements.
We have made significant progress in regards to Lawnchair development, and we are now actually developing Lawnchair 13 (with A13 QuickSwitch support) and custom-made no-root global search. Stay tuned for more updates and sneak peeks.
Coming soon to a lawnmower near you™
(And no, we are not dead. Also No ETAs.)
Then in December:
Hello again!
This time around, we are now developing Lawnchair 14 (with A14 QuickSwitch support). Alongside that, we are also re-adding an option to Hide Dock and options for custom Feed Providers, alongside other new features (we wont give too many spoilers 👀)
We also plan to support QuickSwitch for Android 11 to Android 14, so you can use Lawnchair with QuickSwitch on all your recent devices. (We will prioritize A12.1 to A14 first though).