These guys are planning to fly a prototype in 2023. https://orbitalassembly.com/

That's awesome! At least the prototype part for an automated truss build that they have the engineering for. The subsequent project timelines seem pretty fanciful, like we've built a truss then "hey presto", Pioneer station appears. That then made me question the initial prototype (which is q4 2023 so really 2024/2025). Have you been following this group for a while?

No, I just found out about them.

You wouldn't need an entire wheel, just two equally weighted compartments spinning about a centre point. In theory that's far cheaper. Perhaps you would purposely pump fluid back and fourth to maintain the correct centre of mass.

You could imagine a system where you 'space elevator' objects and people via the connecting cabling, whilst pumping fluid to offset the mass. You would likely want each side to be manned by two people.

You could later add more modules if designed correctly too. They would likely approach and attach to the centre (in a pair, one either sude), match the spin and then slot into their respective 'slots' and rotate on an arm.

It is prohibitively expensive until SpaceX's Starship brings launch costs down further.

It depends on what level of gravity is needed. The mass scales dramatically with acceleration.

And that it's big and heavy.