Attention and stewardship are not universal.
1. "This one issue is what is stopping me from using this product. Is this current method preferred by your users or do you have any other reason to not want to change?"
2. "The proprietary solution costs $X per month. Is there any way to sponsor development? I am willing to give $X/n (where n is whatever number you are comfortable with) per month to get this issue merged and to have some sort of prioritization when triaging issues.
3. Failing those: write a blog post and propose a fork. This is usually the quickest way to get a reaction from narcissistic developers.
Depends on the PR. Bugfixes sure, but new features mean more work for the maintianer in the future.
Speaking as a project maintainer that is starting to see some traction: I'd love to see people coming with PRs for features. It would mean a big amount of validation.
People have a finite slice of their life to give you for nothing. Putting specific suggestions on the issue tracker seems more respectful of their time.