Using digital filter could you improve SFDR?
For ADCs, the decimation filters help remove spurious that fall outside of the Nyquist rate of the signal post decimation. This isn’t true for DACs as the harmonics and IMD products are generated by the device are typically due to sampling and the analog output stage which is downstream from where any digital filtering could be performed. But filtering the DAC analog output may help, especially to reduce the image frequency. But in both converters if you perform good frequency planning, you can get better “in-band” SFDR.