Am told the Mac Studio (smaller Mac Pro/more powerful Mac mini) plus the new monitor running iOS are “ready to go” - so I believe they should arrive tomorrow.
The new 'Mac Studio' is said to feature the equivalent of either two or four M1 Max chips. It's also likely to get more I/O than the M1 Mac mini.
Predictions for the monitor are less clear. A recent report from 9to5Mac claimed that Apple has a 7K display in development; however, this resolution seems high for a 27-inch monitor.
Despite rumors of an imminent M2 device, Gurman now thinks that may not make sense for tomorrow.
Another note: I think it will be odd for the M2 to be announced alongside an M1-series Mac mini/Mac Studio/Small Mac Pro — so maybe we should look for that as part of the May-June cycle. On the other hand, Apple is testing M2 Macs (8 CPU/10 GPU cores) against App Store apps now.