The BCM4776 was announced on 8 Jan 2020 in GPSWorld. It is the second generation dual-band GNSS receivers from Broadcom.
The BCM4776 is also described in the GNSS User Technology Report 2020 / issue 3, published by EUSPA. See page 34.
There are 4 different chipsets in the BCM4776X family - BCM47762 (single-band), BCM47764, and BCM47765 + BCM47768 (dual-band).
The GPSTest Database shows the BCM4776 in various Android phones:
The BCM47762 is a single-band GNSS chipset supporting GPS, GLONASS, BeiDou, Galileo, and QZSS.
Several watches use the BCM47762, including:
Synaptics currently produce and sell the BCM47762, but it is called the SYN47762.
The BCM47764 is a GNSS receiver supporting GPS, GLONASS, BeiDou, Galileo, and QZSS.
It is used in the Apple Watch Series 7 and mentioned in a device analysis on iPhoneWired.
The BCM47764KUBG can be found on websites such as integrated-ic.com, chinax.com, and hkmjd.com.
Aside from parts websites it rarely appears in Google results, possibly specific to Apple watches.
There does not appear to be a Synaptics equivalent of the BCM47764, likewise with the BCM47754.
The BCM47765 is a second generation dual-band GNSS chipset supporting L1 + L5, still showing on the Broadcom website as “Active”. It is used in the Quectel LC29D(B) module, detailed in specification and product overview documents, which shows a 10 Hz update rate.
The BCM47765 appears in several Google Pixel products, including:
Synaptics appear to produce and sell the BCM47765, but calling it the SYN47765.
The BCM47768 is a second generation dual-band GNSS chipset supporting L1 + L5. It is used in the Quectel LC29D(E) + LC29D(F) modules, detailed in the IoT & M2M Modules product brochure v6.7, and shows a 10 Hz update rate.
The Xiaomi Watch S1 uses the BCM47768, clearly shown in a Chinese teardown.
Synaptics currently produce and sell the BCM47768, but it is called the SYN47768.