Ubuntu seems to be missing Vendor-supported drivers in 20.04.1 (as in DCP9055CDNlpr-1.1.1-5.i386.deb). The issue can be paraphrased as 3.2 < 11.5, which seems impossible, unless a single digit is used for holding the version number.

That package is 32 bit (as shown by "i386" in the name). Are you running 32 bit OS or 64 bit OS? If 64 bit then you may be trying the wrong package for the drivers.

3.2 is < 11.5 but I don't know where the error is coming from since you did not copy the full command nor error message.

I have a 64-bit OS. It's 32-bit only, as that is what they provide. It installed on Ubuntu 18.

3.2 is greater than 1.1.1-5. But I don't understand what you're paraphrasing.

The issue is (I suspect, but don't know):
With a single digit for version 3.2 is less than 11.5 (3 < 1).
With multiple digits the issue does not arise.

The complete error is

shakespeare@RYZEN:~$ sudo dpkg -i --force-all dcp9055cdnlpr-1.1.1-5.i386.deb
(Reading database ... 570920 files and directories currently installed.)
Preparing to unpack dcp9055cdnlpr-1.1.1-5.i386.deb ...
Unpacking dcp9055cdnlpr:i386 (1.1.1-5) over (1.1.1-5) ...
Setting up dcp9055cdnlpr:i386 (1.1.1-5) ...
mkdir: cannot create directory ‘/var/spool/lpd/dcp9055cdn’: No such file or directory
chown: cannot access '/var/spool/lpd/dcp9055cdn': No such file or directory
chgrp: cannot access '/var/spool/lpd/dcp9055cdn': No such file or directory
chmod: cannot access '/var/spool/lpd/dcp9055cdn': No such file or directory
shakespeare@RYZEN:~$ sudo dpkg -i --force-all dcp9055cdncupswrapper-1.1.1-5.i386.deb
(Reading database ... 570920 files and directories currently installed.)
Preparing to unpack dcp9055cdncupswrapper-1.1.1-5.i386.deb ...
lpadmin: The printer or class does not exist.
Restarting cups (via systemctl): cups.service.
Unpacking dcp9055cdncupswrapper:i386 (1.1.1-5) over (1.1.1-5) ...
Setting up dcp9055cdncupswrapper:i386 (1.1.1-5) ...
Restarting cups (via systemctl): cups.service.
lpadmin: Printer drivers are deprecated and will stop working in a future version of CUPS.

I did (without success):
shakespeare@RYZEN:~$ ls /var/spool/lpd
ls: cannot access '/var/spool/lpd': No such file or directory
shakespeare@RYZEN:~$ sudo mkdir /var/spool/lpd
[sudo] password for shakespeare:
shakespeare@RYZEN:~$ sudo dpkg -i --force-all dcp9055cdnlpr-1.1.1-5.i386.deb
(Reading database ... 570920 files and directories currently installed.)
Preparing to unpack dcp9055cdnlpr-1.1.1-5.i386.deb ...
Unpacking dcp9055cdnlpr:i386 (1.1.1-5) over (1.1.1-5) ...
Setting up dcp9055cdnlpr:i386 (1.1.1-5) ...
shakespeare@RYZEN:~$ ls -l /var/spool/lpd/dcp9055cdn
ls: cannot open directory '/var/spool/lpd/dcp9055cdn': Permission denied
shakespeare@RYZEN:~$ sudo ls -l /var/spool/lpd/dcp9055cdn
[sudo] password for shakespeare:
total 0

It is not 11.1, it's 1.1.1. Version 1, not 11.

If you're going to argue about version numbers it's 11.5 (not 3.2). There was a 1.1.1-5 in the DCP9055CCDN driver as well. I've upgraded Xubuntu, without success, I have a GP106, and a 4K display.

Do you have a 32-bit system? The .deb package you're trying to install is for 32-bit systems, indicated by the i386 in the filename.

I have a 64-bit system. All that's provided is (for the actual drivers) a lowly 32-bit system (hence the i386 of the title). I had it working in Xubuntu 18 and here I am looking at an Xubuntu 20 system with the drivers failed.

Well, it is Ubuntu, so perhaps you're out of luck. I don't have the ability to test those drivers on my systems. I did note this line in the error messages, though.
That version of CUPS may have arrived.