In the AD7380 datasheet (Figure 18) the SNR vs input frequency rolls off and there is no data provided above ~100 kHz. Is there a reason for this?
What kind of SNR could one expect for a signal at 1 or 2 MHz?
You can do normal averaging oversampling with the AD7380 that is up to 32x OSR. Although this may have trade-off with the throughtput rate.