DC to DC boost converter low frequency
Consider that:

a DCDC converter that switches at a low frequency could actually generate more EM radiation than another DCDC converter that switches at a higher frequency but where measures have been taken to reduce EM emissions.

The speed at which the switching is done is quite important. If you switch fast at a low frequency, you will have lots of harmonics. I once worked on a product where the 283rd harmonic of a DCDC converter switching at 600 kHz was the issue.

in your design you have to make sure that the current loops that generate the EM emissions are short and small. The larger they are the more they will emit as they're basically an antenna. Larger antenna: more emissions.

consider shielding if you expect EMI issues

use a DCDC converter which uses an external clock so that you know at what precise frequency it is switching. You can then use it at a frequency where the clock and its harmonics are no issue.

consider a DCDC converter that uses &quot;spread spectrum&quot;, the clock isn't constant but varies somewhat and that will spread the EM emissions over a wider frequency range so the power is more &quot;spread out&quot; over frequency which could help in some cases.