Hello,
I work on Pharo, an open source derivative of Smalltalk. Pharo is licensed under MIT hence most of my work needs to be licensed also under MIT.
However, time to time I have some projects in my free time that I made for my personal usage or for friends, and in those cases I am not OK with my work being used by for-profit project not giving anything back.
I would very much prefer to use GPLv3 on those cases, but my understanding of licensing is very poor and I have been told there is a "virus" behavior on GPLv3 that may prevent people to use at all what I do, and that's not my intention.
First, thanks for working on Pharo, what an amazing environment.
I am not a lawyer so you should double check.
For GPL, indeed the image as a whole would be GPL. If the personal project is more of an “executable”, it might be what you are looking for, any further image modification would have to be released under the GPL as well.
If the project is more of a “library”, you might or might not prefer the LGPL. In this case I feel like https://www.gnu.org/licenses/lgpl-java.en.html would apply similarly to Java. As long as you can load the image and change the original library code, other code is not restricted on the license.