So I've got a Macbook Pro 13' 128GB and use it primarily for development.

Thing now is that the other storage keeps increasing and re-cleaning it again and again using DiskSweeper is a task , So I bought a 256GB External SSD and moved and setup XCode on it. It's working but I can't really eject the disk anymore as I had to re-setup XCode again if I did forcefully eject it.

Now the question, I've seen people here have dual installations on mac. Am I restricted to have the external connected even then? then I guess the XCode approach is simpler but if I can eject the external whenever I want then I think I'll go ahead with the dual install.

If someone has a better alternative, let me know

UPDATE:
I ended up installing the os on a the external device and can remove the device and boot from it whenever I want. Installing Xcode and huge projects on this from now on, there's a slight performance lag because of the difference between a sata connected SSD vs a USB C / Thunderbolt connected ssd