Including the ATmega328PB as a further Nano variant

Why is there no official support for the ATmega328PB in the Arduino IDE? The processor is a typical AVR!
There are several packages (Pololu, Watterot, MiniCore, ...) with which the IDE is actually unnecessarily inflated!
I have a Nano clone with the ATmega328PB from China, it works as a "normal" Nano, but without being able to use its extended functions.

Do 'Arduino' make any boards that use the ATmega328PB ?

Good question! I remember a wish to replace the 328P with the newer 328 PB. This could give the "old" Nano another push.

There are at least three 328PB cores

All companies sell 328PB Arduino compatible boards, The AVR one is cheap (if available)

https://www.digikey.de/products/de/development-boards-kits-programmers/evaluation-boards-embedded-mcu-dsp/786?k=328pb

Don't forget the best of all (already mentioned in passing by @RudolfAtRTC):

it is simple to use a custom board with existing official boards package:
https://arduino.stackexchange.com/questions/54484/adding-a-custom-board-to-the-arduino-ide/

My experiance with MiniCore: It compiles, but the upload fails with all offered Programmer variants

In order to gather more information that might help us to troubleshoot your problem, I'm going to ask you to post the full output from the upload when in verbose mode.

Please do this:

  1. Select File > Preferences from the Arduino IDE's menus.
  2. Uncheck the checkbox next to Show verbose output during: compilation
  3. Check the checkbox next to Show verbose output during: upload.
  4. Click the OK button.
  5. Attempt an upload, as you did before.
  6. After the upload fails, copy the full text of the black console pane at the bottom of the Arduino IDE window and paste it in reply here.