I have an Idea for a new board!
This board will be based on the powerful Atmega32A chip.
This specs of the board:
Main chip - Atmega32A PU
USB chip - Atmega16u2
USB connector - USB 2.0 Type A/B
Power Jack - Barrel
Board size - about the size of Arduino Mega
Pins - One rail for power, reset, and Aref.
One seperate rail for Port A. (I/O pins)
One rail for Port B and corresponding pins.
One rail for Port C and corresponding pins.
One rail for Port D and corresponding pins.
One ICSP header for the Atmega32A
One ICSP header for the Atmega16u2
The corresponding pins should be marked with the the name of the pin, which is used for the communication protocol (UART, SPI and I2C)
What do you think about this board? I hope Arduino makes this board.
The creator of the popular MCUdude boards platforms makes an ATmega32A board:
Arduino Forum moderator CrossRoads also makes some ATmega1284P boards that would work with an ATmega32A if you don't need the full capabilities of the ATmega1284P: http://www.crossroadsfencing.com/BobuinoRev17/
These don't exactly match your specifications, but they come pretty close. I own both the MCUdude board and the CrossRoads "ATMega1284P Duemilanova-style" board and they are both very nice.
There have been multiple suggestions for Arduino to make an ATmega1284P-based board over the years. I haven't seen a request for the ATmega32A before, but I'd guess it would get the same response. You are always welcome to design your own board.
I'm more a fan of the ATmega1284P than the ATmega32A. My use case is for when I am designing a board from scratch for a specific project. In this situation where I'm spending a lot of time on the project, it's well worth it to me to spend a little extra money to have the increased capabilities of the ATmega1284P (when compared to the ATmega32A). Even if I don't need those capabilities immediately, I may later want to add additional features to the project and would not want to run into memory shortage just because I decided to save a few dollars on the BOM. However, the reasonable price, nice number of pins, and DIP package availability of the ATmega32A does make it a bit attractive to me. I have a few of these chips on hand, even though I've never done anything beyond some basic blink-type things with it.
If you're interested in learning more about the use of the ATmega644/1284 family of microcontrollers in Arduino boards (which is relevant to the use of ATmega32A as well due to it being pin compatible), check out the contents of this repository:
There is a vast industry based around turning ideas for electronics products into real hardware. To keep it local, I'll point you to the "Gigs and Collaborations" forum board: https://forum.arduino.cc/index.php?board=26.0
Assuming you are able to pay for their services there are certainly people following that section of the forum who will be happy to design such a board for you and connect you with PCBA companies that will manufacture the design in any quantity you like.