The example i will give will be for a simple tool on github called ssh-audit , but this process can be made for any other tools you may want to add to your menu .

Link of the tool : https://github.com/arthepsy/ssh-audit

In my case i have cloned the tool to a specific directory i have in my system for that , but anyone can clone it to whatever place you want in your OS .
My example directory is in : /tools/ssh  directory
First of all go to your target directory where you want the tool to be cloned and issue the command :

git clone https://github.com/arthepsy/ssh-audit.git

like it is in the next image :

Next step is to test if tool is working or not , this is important because some tools need dependencies to run , but in this case this tool already its dependencies installed in my OS .

Ok , now that we see that the tool is does not have any issue on starting up , we need to test it on a real ip address to see if any error popup or not during the scan .

This ip i used was a random ip i found with port 22 opened .

Now that we can see the everything is working fine , we will add the tool to our Devuan XFCE4 menu .
To do that open the app in (Accessories/Main Menu)

After main menu is opened , click on "New Item" and this new window will popup :

In the Name field put your tool name , in this case "SSH-Audit"
on the command field put this next code :

sh -c "cd /tools/ssh/ssh-audit && ./ssh-audit.py -h;${SHELL:-bash}"

this code may change depending where you have your tool installed .
if you have for example your tool installed on this directory "/root/ssh-audit" , then the code must be :

sh -c "cd /root/ssh-audit && ./ssh-audit.py -h;${SHELL:-bash}"

the CD command tells the shell that will open to navigate to that directory , and the "&&" = to execute also the command ahead .
Witch is "./ssh-audit.py" .

Select also the option "Launch in Terminal" , because this tool is a terminal tool and not a graphical tool .

To add an icon to that tool , then click on the default image on the left , and select the image that you want to add to that shorcut from your OS .
by default , icons in linux are located in "/usr/share/icons" directory , but if you found a cool image on the web , then save that image to your Hard disk , and select its location and filename , like i did with this next image :

On this last window you see a big image because i selected an image from the web and not an icon , but the main menu tool will resize it when you save you new menu shortcut .

Press the button "OK" to save your new shortcut .

Now , if you open your Devuan Menu Again , you will see your new tool shortcut there  , like it is in my next image :

After this point , anytime you want to use your tool , everything you need to do is launch it from your Main menu shortcut , like it is in my next image :