Would it be possible to forward MS Unit tests from an EXE to a DLL?

I have an application where there is a mess of code that has a bunch of non-isolated components. This makes things difficult in terms of doing some unit testing. So along with some unit tests in their own separate test DLL, I'm trying to also create some tests within the application DLL. The application DLL is normally invoked from an application EXE.

For some background, this code is 20+ years old written in native C++. I cannot execute the tests in the DLL directly as the framework is not setup, so any calls executed within the DLL will not execute correctly. I've unsuccessfully tried to do this already, but maybe I need a more fundamental understanding of the MFC framework to do this.

A colleague suggested that maybe it might be possible to have the vstest.console somehow run the tests through the EXE where the framework can be brought up, run the tests through the EXE, which are then forwarded to the DLL, and then have the test results returned back through the EXE to vstest.console, effectively making the EXE a proxy of sorts.

I'm thinking that this might be a longshot, but I'm at a loss as how I can run the tests in the DLL properly. Could it be done? Is there a better way?