Ok so on further investigation I noticed that on all of my other hosts mycommand is indeed in /usr/bin not in /usr/local/bin. The reason for this is, that every package manager has installed it in /usr/bin except for the weird "software store" (or whatever it is called) from synology.

I went the "dirty" way and just created a symlink: /usr/bin/mycommand > /usr/local/bin:

ln -s /usr/local/bin/mycommand /usr/bin/mycommand 

Now for everyone facing a similar problem: there is a reason why a /usr/local/bin exists and there might be risks with my solution. But it's the easiest and fastest and I already spent way to much time on this problem. In my situation all ssh-keys will be limited anyways to one command only so I don't really care.

Anyways: if you want to read more about the difference between those two locations I recommend this post: https://askubuntu.com/a/308048

Ok so on further investigation I noticed that on all of my other hosts mycommand is indeed in /usr/bin not in /usr/local/bin. The reason for this is, that every package manager has installed it in /usr/bin except for the weird "software store" (or whatever it is called) from synology.

I went the "dirty" way and just created a symlink: /usr/bin/mycommand > /usr/local/bin/mycommand:

ln -s /usr/local/bin/mycommand /usr/bin/mycommand 

Now for everyone facing a similar problem: there is a reason why a /usr/local/bin exists and there might be risks with my solution. But it's the easiest and fastest and I already spent way to much time on this problem. In my situation all ssh-keys will be limited anyways to one command only so I don't really care.

Anyways: if you want to read more about the difference between those two locations I recommend this post: https://askubuntu.com/a/308048