The 2025 iPhone SE is said to be the first shipping device for both the new Bluetooth/WiFi chip and the 5G modem.

Cost is certainly a factor, but it doesn't take a lot of searching to find people designing and building devices saying that the existing third party hardware and firmware implementations for Bluetooth are problematic.

I don't think the Android/Pixel guys were daydreaming about ditching Broadcom for no reason.

I seem to remember discussions the Google Glass people posted here about their own issues with keeping a stable Bluetooth connection with the available third party Bluetooth chipsets.