I have used Xojo in the past, mostly with a pro license, but I am now mostly retired and develop apps only for my own in-house photography business. No software sales.
With the Lite License (for Desktop MacOS) can I still install it on my desktop as well as my laptop?
You only get one machine activation with Lite. You would have to deactivate one machine before moving to the other. Doable, but a hassle.
There’s a comparison table available in the store. This link might work, if not click the “Compare Features” button underneath the heading “Not sure which license?”
The license is which platform it will build for. You can run the IDE on any platform but you are limited to building only for the platform that you buy.
It’s not really an advertised thing, but in the past I was able to purchase an extra machine activation for a license, for a nominal fee. I don’t know if they still do it or not, or whether it can work for a Lite licence.
I have the Desktop version and I always build applications on my Mac to make Mac and Windows applications. I use Xojo IDE on Windows to test the Windows version of my applications, I rarely build on my PC-Windows.
A developer who buy the light Mac version can only build application on his Mac, he cannot build on his PC-Windows. But it is not clear for me if he can build Windows version on his Mac?
Of course, you can develop and debug on both machines, but you can only build on one of them with the Lite license. There is nothing about the OP question that suggests multiple platforms.