The USB-C ports on the M4 iMac support
- USB devices
- Thunderbolt devices
- DisplayPort capable external monitors
So any USB based printer can be directly connected to the Mac. At worst, you will need a USB-A to USB-C adapter for the existing cable. If you are using a USB-C dock or a Thunderbolt dock, you can direct attach a printer to a USB-A port on the dock.
Your DVD drive - This also means you should be able to attach your USB based Apple Super Drive DVD. All you need is a USB-A to USB-C adapter, or a dock that has USB-A ports. What I DO NOT know, is whether the M4 iMac will know what to do with the DVD drive.
Pointer to USB-A to USB-C adapters (click here)
Network Printer - Many of the other posts mention WiFi or Ethernet network connected printers. They are an option, but are not essential. One advantage of a network connected printer is that it can be used with all the personal computers in your home. And the printer does not need to be located next to your Mac. For example, my network attached printer is in the closet next to the front door. It is out of the way, and the laser printer toner smell is kept out of the rest of the house. I use a Brother Laser printer with AirPrint support.
AirPrint - Other posts have emphasized using a printer with AirPrint support. AirPrint is the best way to future proof your printer, even if the printer vendor stops supporting the printer, the AirPrint protocol will allow the printer to continue being used with the Mac. In addition, iPhones and iPads can wirelessly print to AirPrint capable network attached printers.
I would also like to point out that before my current printer I was using one of the first generation AirPrint cable printers, and it works flawlessly for 12 years, long after the printer manufacture stop supporting the printer. If your printer has AirPrint support is should continue to work with your future Macs as long as the printer continues to function, and you can get supplies for the printer.