https://hackaday.com/2022/11/15/getting-to-the-heart-of-a-ba...
All based on RDA1846 introduced in 2008. Inside this chip you will find LNA, mixer, PLL, ADC/DAC, and a DSP. Complete dual band radio on a chip. Cheap too.
https://datasheetspdf.com/pdf-file/1473066/RDA/RDA1846/1