That’s really odd, since professionals use them all the time.
I cannot imagine why. I regularly print exhibitions using a MacBook Pro 16" and an Apple 27" Cinema Display. No problems at all and I usually never even need to download a printer driver - macOS seems to know most printers already.
This is not the fault of running a Mac. PL5’s print module isn’t worth the electrons it consumes.
I have just bought a new Canon Image PROGRAF A2 printer and it comes with a print layout utility, which I now use. So far, I haven’t even needed to profile the printer but have the means to so do if needed.
Before that, I was running an Epson SC-P600, exported a resized version to TIFF at 240ppi and used either Preview or the ColorSync utility, both of which come free with macOS. No problems with printing using ICC profiles or the Advanced B&W mode.
I can’t speak about Nik Collection because, although I have it, I never use it - PL does everything I need.
Rather than throwing away a perfectly serviceable iMac, if printing is the only pinch point, why not be a bit more specific about your problems and let’s see if we can help.
I used to use Windows from version 3, right up to XP, developing software. I also used to look after the Windows machines for several clients and was never out of work, trying to keep up with all the problems that updates caused and generally setting them up because it was far from intuitive for the average busy business owner. One of my clients had the motherboard fail on two Windows boxes in the same day. I suggested moving to Mac and, after a couple of weeks of him cursing because everything was done differently, he suddenly realised that 1. things were actually easier and 2. he no longer had to call me in to fix them.
The M1 chipset is new and there was always bound to be teething problems with existing software, especially apps like PL which previously made intensive use of the GPU. There are others on this forum who are running M1 Macs who would be more than willing to help if you can supply accurate details of any problems you are experiencing with PL.