a bit of text you can send to them by whatever secure side channel you want down to handing them a flash drive
Normal non-technical people are never going to do this. It needs to be easy as clicking a button, otherwise it will never happen for them. Again, this is a neat technical solution but it completely forgets the human.
Yes. Describe it as best as you can and let the developer reach out to you if you want. A good maintainer will ask follow up questions for more specific stuff that you may not have provided at the start.