I’ve a couple of ideas I’d like to run with/ projects coming up that I would like to at least have the opportunity to make a few pennies off of for all the work I’ll be putting into it. If I were to create the software using JUCE in GPL mode, release all source code and give attribution where needs be, is it fair/ legal to ask for a donation towards the development of the software (basically the same way Arduino release their IDE)?
If you’re part of a bona fide educational institution then you can apply for an Educational License which will be free of Minimum Commitments or Revenue Limits.
Otherwise, if your total revenue (including donations) from JUCE-based products is less than $50k then you can use JUCE for free under the terms of the Personal License.
To add to what Tom said, if you are releasing the source code alongside the software, you are free to monetise it in any way you see fit.