Install tiers app on DDMC AMI

What is your guess? As you only ask this for the DDMC? Did you wonder the same about DDVE, as that is the reason to use a DDMC, to manage DD systems?

As DDMC is also running on DDOS, just like the physical DD systems and virtual DDVE's, I would reckon it cannot be done as there is only an option to install DDOS related rpm's or MDU (minimal disruptive upgrades) patches, that at time are not more than adding a script to a DD. So not unless Dell would provide something to deploy any non-Dell software on such a DDMC appliance, it would not be possible to do anything on a DDMC nor DD(VE).

DDMC, like DD systems, have a very restricted shell, and no normal shell access, unless provided (temporary) through Dell.

Beckons the question also what you are even trying to protect, as a DDMC itself does not actually host any data (except its own configuration and collected history) as actual data is stored on DD systems. It is only about managing DD systems (and nowadays also to provide services for the DD Smart Scale solution).

What would you expect to be able to be done for any other appliances, regardless if hosted on-prem or in the cloud, or physical or virtualised? You would expect them to offer save methods to login to them to be able to manage the systems they are supposed to manage in case of DDMC. And for example host them in separate management vlan's to access the DD systems they are supposed to manage, using separate login credentials, choosing security best practices like not integrating access using the normal production AD for example.