You still haven't shown me anything that contradicts what I said and I *believe* to be true. (But if you can find it, I'm open to it.)
I don't really care what you believe. It's what the FAA says is true that matters. And I've given you that - If written English from the FAA doesn't do it for you, nothing that is said here on PoA will ever convince you.
I have continually stated you cannot file/accept and IFR Clearance in a VFR only aircraft. Your quote says what I've been saying. "...Any aircraft that meets the equipment requirements..." There's no one from column A and one from B. If the plane is not IFR capable, or can not "meet the equipment requirements" you may not file/accept and IFR Clearance. You can fly under the hood all you want in VFR conditions
"Meets the equipment requirements" does not mean the same thing as "Is IFR certified."
Going back to an example already used in this thread: The Diamond DA20. It is not IFR certified because it's a composite aircraft with no lightning protection. The DA40 has a metal mesh under the skin for that reason. You can put the EXACT SAME instruments in both and the DA40 will still be IFR certified and the DA20 won't be.
But, if you have all of the instruments from 91.205(d) in a VFR only aircraft like the DA20, the FAA allows you to file and fly IFR. You just can't go in IMC. Hope that makes more sense now.
Perfect example... A couple of years ago we did a X-US flight in October. I filed IFR on all legs and as it turned out on 99.9999% of the days we were flying for the entire trip in the the big loop around the US was not only VMC, but CAVU!! But I did end up Logging 0.1 Actual. Leaving KAWO if I had gone N, E or S, I would have been in VMC. But ATC had me turn West, so I climbed for a few minutes through some clouds along the coast. If you are on an IFR Flight Plan, ATC does not ask you if you can accept a turn to the right or left, you are expected to turn even if it is into IMC. (Granted there may be some reasons you may say "unable") They don't want to hear "sorry that will put me in IMC and this plane isn't IFR Certified. In fact, I'm sure you'd get a call or a visit from the FSDO.
"Unable, weather. We can turn North, East, or South."
Well... If you're going to quote a Legal Interpretation, make sure you have the latest. Pratt in 2022 rescinded the Theriault interpretation.
Pratt caught my eye mostly because I know Mike Pratt.

But yes, I read that, and no, it does not change things because 8900.1 5-439 still exists.
Pratt also doesn't say anything about the VFR aircraft being operated in IFR portion of Thierault.
There is a very important legalize in there "...However, we caution that the pilot in command must ensure compliance with the flight rules and not to expect special handling from Air Traffic Control..." So even though the lawyer appeared to have ignored the Regs (91.205, 91.215, 91.411 and I'm sure others), if you did file, you could still be violated if you're not IFR capable.
And an aviation lawyer fresh out of law school should be able to successfully defend you on that one given the documentation that has been provided here.
No, you can't "expect" special handling. If you can't do what ATC says, you need to be willing to cancel. Simple as that.
A slight tangent question: In the sub paragraph quoted above does the pilot in command (PIC) need to be properly certificated and current to be operated on and IFR flight plan under IFR in VMC or would the instrument rating alone be sufficient to file and accept an IFR clearance?
Yes. Nothing about any of this changes the necessity of the PIC being certificated and current to operate under IFR.
is it legit to say unable to atc instructions that would put you in imc when you are on an ifr clearance? doesn’t seem to me like it would be.
Absolutely. Just like if you were going to be put into ice, thunderstorms, terrain, or anything else. I've said "unable" on an IFR clearance far more often than when VFR...
What percentage of a typical IFR training course can I accomplish effectively in my aircraft, versus how much would I need to obtain another aircraft for?
Let's say it's 50/50, or 75/25. I can do the math from there to see if the rental cost savings pays for the equipment expense.
I think it largely depends on your instructor, so you really need to talk with them instead of us.
The more I look at that GPS 175, the more I like it. Price was deterring me, but then I realized I could skip the Aera 760. Marginal cost over my planned VFR upgrade would be around $4K, but it would be future proof, unlike an obsolete GPS and an old NavCom.
Garmin's entry into the low end of the market was a very welcome surprise, and they've got some good stuff for relatively reasonable prices.