I kinda like this idea (it reminds me of cPanel's MultiPHP feature, or Plesk's way to handle these kind of things per site/domain) and have few times actually hoped that there would be this kind of feature.
Even if this wouldn't be a part of Laragon, I'd like to chime in with few observations.
After thinking this a bit, I think there might be some problems which could cause some difficulties with implementation.
Let's say I have 2 different projects:
- Project 1
- PHP 7.2
- MariaDB 10.2
- Nginx 1.13
- Project 2
- PHP 5.6
- MySQL 5.6
- Apache 2.4
How would Laragon handle this kind of thing if I'm working on these projects in the same time?
Option 1
Laragon would load PHP 5.6 & 7.2, MySQL 5.6, MariaDB 10.2, Nginx 1.13, Apache 2.4 etc. daemons to memory? This would probably cause some conflicts and use lots of resources. This is the way cPanel and Plesk are handling these kind of situations (designed to work in this way), IIRC (with a smaller set of options to choose from).
Option 2
Laragon would hotswap daemons depending which site we are loading, but this would probably be very slow and inefficient way to handle this.
Option 3
Laragon would give you an option to choose which project is active (only 1 active project) and load daemons which are needed.
Option 4
Something else?
What if I have 20 projects which all have slightly different setup? Let's say total of 6 different PHP versions, 4 different HTTP daemons, 3 different DB daemons, etc. You get the picture 
Option 3 would probably be the easiest way to do this, even though it would decrease Laragon's flexibility a bit.