A wireless engineer with the pseudonym "Sellers Circuits" has developed his own signal generator using a Raspberry Pi RP2040 microcontroller and an Analog Devices AD9833 signal generator chip.
The generator is a low-cost device suitable for use as a diagnostic tool or for educational purposes. The board is controlled by the Raspberry Pi RP2040 microcontroller and with the AD9833 using a MicroPython program. The AD9833 can generate sine, triangle and square waves with a maximum theoretical frequency of 12 MHz.
The finished board can generate waveforms of arbitrary frequency in sine, square, and triangle formats. It is worth noting that at 1 MHz and above, the steps in the output signal become noticeable due to the sampling rate of the device. More details about the project and the board schematic are available on the SellersCircuits blog, and the assembled board can be purchased on Tindie for $35: https://www.tindie.com/products/derpman/diy-waveform-generator/.