I know that the information has been posted recently showing the T4.x ports.
There are actually 4 ports: Ports 1-4 (or in high-speed mode) 6-9. Most of the time on Teensy 4.x we are using the GPIO in high speed mode so we use the GPIO6-9. Where 1->6, 2->7...
I usually look at my excel documents, for this which has a few different pages for T4.1 including one like:
Which is a little more complicated to read, but gives more details about each pin.
You will see a column labeled GPIO (actually 2 columns, one for pins on left other for pins on right).
So you see that the Teensy pin 0, on this is showsn as 1.3 This is Port 1 pin 3. Again, sorry for this confusion, So in practice this is port 6 pin 3.
I left this these using the 1-4 ports as, this is how they are referenced in the Reference Manual which you can download from the Teensy 4.1 product page.
I know there are other tables that have been posted showing which pins are on Port 6 which on 7, 8 and 9
Hope that helps.