@smihaila,
Could you please share how you finally solved it?
When I execute WinPerReleaseMsi.msi, the installation starts, but I then get a Turbotax error window (asking me to submit what I was doing when error occurred)
Sorry, it's a tad complicated to explain the process of making it work - would require posting a big page of instructions and a longer than 1 hour of explanations.
The biggest issue with the pesky "WinPerReleaseMsi.msi" is that the US version of the product was not designed to be self-contained, possibly due to making one code base per-se, and driving the product price and flavor based on a separate configuration, which lies outside that MSI file. And unfortunately, it is still the "setup.exe" and "TurboTax 2020 install.exe" driving the MSI, and injecting the most essential part of the setup, which is the product type and limitations. It's like a sort of provisioning in a way. And those two .exe files are exactly the primary ones preventing Win7 use.
Btw, the Canadian version (of the MSI) is simpler, straightforward, fully self-contained, and robust. Not to mention more efficient and fast code (real men do not program in .NET or Java, but in C and C++ ;-) ).
You also need an open-source utility named dnSpy (as in Dot Net Spy), available here (32-bit edition is needed):
https://github.com/dnSpy/dnSpy/releases
I've managed to isolate the outcome of all work in the form of a full set of files (totaling about 400 MiB in zip form), which can just be copied to your win7 OS, and have the TurboTax 2020 Deluxe edition, just run from that, self contained and without any explicit installer or "installation".
So, it looks like a "portable format" in a way (similar to when you run all sorts of standalone utilities, without an install). I could post it somewhere upon request, but I don't wish to get into copyright shennanigans...