shit here could be wrong/misleading; take all this with a grain of salt.

rule overrides seem to be errors now

dexpreopt_bootjars has now moved to the soong build system

All modules to be added as bootjars need to migrate to Android.bp rules

They also need to be marked as installable

installable: true,

Else they aren't picked up for bootjar dexpreopt at all

Also, much like last time, snooping around base, SystemUI and Settings, doesn't look like Google pushed any major visual changes on the preview tag.

You can add

BUILD_BROKEN_DUP_RULES := true

to work around this for the time being.
But yeah, if you have this, I guess it's time to fix your build rules.

Similarly,

BUILD_BROKEN_PHONY_TARGETS := true

Particularly useful if you're trying to use the current kernel.mk rules. Again, this should be fixed up properly and this is a mere workaround.
Google was nice enough to "warn" us this way, I guess 😆

Oh I should probably add in a few older findings here too

soong json generation has improved a lot since pie. There are now saner functions to handle this. For reference, see this.
So, now our custom map's config.mk would looks something like this:
https://github.com/PotatoProject-next/vendor_potato/commit/6ca5af3c9647898ea60feab9c8711fa64333aa06