Is there a way to develop a single houdini file/project? For example can I and a coworker both work on the same file at the same time?

you can version control hip files and other files used in your projects - but two people can't work with the same file at the same time.

Maybe this could be a new feature? Ability to merge two graphs and choosing any conflicting nodes.

There was a Network SOP node for sharing data over a network connection. Was deprecated some time ago.
You can do the same thing better with Python or HDK today.

You can have a single file with multiple external HDAs inside (without exposed parameters) and each of you will update those HDAs. Updating external HDA on shared storage will push the changes to all the scenes where it is linked.
This moves edits outside of hip file into those HDAs.

So when somebody updates the HDA both of you will get those changes.
You just have to plan ahead how do you split those tasks into various HDAs.

Or you can both save and commit changes to the remote repository and fetch each other changes periodically, but you will have to resolve merge conflicts. Not sure if it worths it.


USD is another option.

Are you going for something like Nvidia's Omniverse or Unreal multi-user editing workflow?

Those are good points, that is how we used to collaborate so far. Splitting tasks ahead of time into to chunks and manually merging them.

USD, Omniverse and UE's multi-user are great recommendations - yes, I think that having some mechanisms to automate merging files either into a new environment like Nvidia or just into one houdini hip file would be very useful.