It’s a good plan, but I worry about investing in a temporary solution which is going to lose a lot of value quickly. As it is my intel MacBook Pro 16” won’t be worth much as a trade-in soon, so an M1 Mini would make a better short-term fix, and not lose too much cash in the process.Problem with the Mini IMO is that you will not want to go with a display that is less than retina in resolution. And such a monitor will be costly as it would have to be 5K in the 27" size.
I would wait until WWDC just to be safe. If we don't get the new bigger iMac at the event, and you don't want to wait until the fall, then I would get a refurbished 27" iMac which right now is $1,439. You can manually add more RAM if needed.
But yeah, I really want that retina screen. I could plug my MBP into my 24” old monitor here, but it’s such a downgrade in quality I usually don’t bother.