I think I have a hat to throw in on this one!
What motivates you to create and maintain community nuget packages?
What often would motivate me was to help others who may need something that Kentico didn't have (or would have but farther in the future). I wanted people to stay on Kentico, and also to leverage it well. I hated how many agencies had their own solutions but no one ever shared. I get it from a business standpoint, but I disagreed with the mindset.
How do you expect other developers to use your work, and what is your approach to contributions or collaboration?
I have so many modules, especially in the Portal Engine days. I created what I created to make development easier, solve common problems, and help people stay on / stay up to date with Kentico.
How do you think about long-term maintenance, especially knowing that some projects rely on your package as a dependency?
Honestly, I try not to be "that guy" that builds a package and never maintains it - It frustrated me to no end on the occasions I used a 3rd party package.
So, when I built my systems, I built with a mentality of "Make it so others can use it." Often this would result in complex or complicated packages, which is the down side, it may be harder to use because the feature set is more wide.
I've spent considerable time over my tenure updating packages, and this was back when I had 5+ main custom modules and each Kentico version I had to rebuild, and if a bug came along often having to rebuild and fix older versions and republish. I know I can't expect others to do that, because it's a pain, but I did it.
Overall, I would like to think that my packages were known for being supported, and why in the Portal engine days many used my packages. But I may be delusional. But even if I can solve a problem so 1 or 2 more people can migrate or use Kentico earlier, then it's worth it.
I remember packages like the KX12 to KX13 Portal migrator were massive undertakings but helped a LOT of people (and now Kentico has its own migrator tool, which is awesome!)
I know the Media Library Migrator tool helped a lot of our clients (and possibly others) move from on prem to cloud based easier.
The Baseline project to help those with the "Do we build on KX13 or wait until Xperience is mature" decision back when Xperience was new.
The hardest part though is I put a lot of work into my modules, and often I have very little knowledge of how much they were actually used outside of my organization. I know they were, but I have no way of knowing how many people were able to stay on Kentico, Migrate to Xperience, use Xperience earlier, etc.