This is extremely misleading. In the US, the ATF has stated in past rulings that electronically-fired semi-auto weapons are functionally equivalent to full auto weapons in the case where there is not manual user input per shot. (If there is manual user input per shot, it's not clear from any existing rulings and should be treated as an open question that may get you sent to prison).

Now, the ATF just makes up new rulings all the time and they aren't laws, so "legal" is always a touch fuzzy where the ATF is concerned, but you're probably going to prison for a very, very long time on a weapons charge if you make a remote-activated, electronically-fired semi auto like we're talking about here - the same way you would be if you try to make your own full auto. The exception would be the case where you are legally allowed to manufacture fully automatic weapons because you have an SOT license from the ATF. In the case of the video made in the past few months where some YouTubers mounted a rifle on a Boston Dynamics Spot, one of the YouTubers in question specifically does have an SOT, meaning they can do things that would get normal people sent to prison over an NFA violation.

At the very least, before you do something that destroys your life, call up the ATF and ask them whether what you are about to do is a dangerously bad idea legally.