Due to the fact that Ukraine is a former member state of the Soviet union I guess that they share a lot of military technology with the russians. Maybe this device would jam some of their own technology?

Thanks for the comment. So your last point brings me back to GLONASS only. Yes if the soldiers have (charged) smartphones they might use GPS and/or Galileo, but their military kit will be GLONASS only. If my proposed kit leaves GPS alone then it will allow normal public to navigate normally, and I'll specifically test this.

There are two methods to get it it Ukraine - 1. from where I am, people are driving there. 2. Make the board simple and hackers in Ukraine can make them.

So it would be  a good idea to choose components that can be scavenged from consumer electronics e.g. PLL's synthesisers etc.

Another point to make is that you can bet that GPS and GLONASS are already degraded in the area, maybe up to a 20m radius. It's only the military kit that will be able to resolve down to metre or sub-metre. A +/-20m error in targetting could make the difference between life or death for a defender.

"For what might be obvious reasons I think it would be neat to create a signal jammer specifically for GLONASS"

Sure. I think we all see where your going. It's a nice thought.

However, for example, my several generations old Samsung lists the following as it's "GPS" abilities: "A-GPS, GLONASS, BDS, GALILEO".

I am not an expert in the Russian military but I bet their nav units have are not less capable than my old, consumer grade smartphone.
They have GLONASS in case the rest of the world turns off or scrambles their own nav systems but no doubt they can still use the others.

So you really would have to block them all.

And you would have to get it to Ukraine, unless I guessed wrong and that's already where you are.

And you would have to hope that the Ukranian military, citizen defenders and/or fleeing refugees didn't need nav for their own purposes. That last one could be terrible. Imagine families getting lost and heading right back towards a Russian convoy.

There are even more things to consider. You need substantial RF power to drown out all satellite signals from horizon to horizon. If you cannot get very close to the nav receiver, 20W is nothing. This would sabotage only one specific guidance system and has absolutely no effect on ballistic weapons. Also one should not assume, that the enemy will get lost in the woods without electronic navigation, they know how to read maps. In other words, jamming nav sats is a waste of time and resources.