No problem on the MQA front. I don't use MQA but I'm more than happy to help. I also agree with the "I've paid for it so I'll use it" approach.
What you'll need is software for the RPi that's "imaged" on to the micro SD card - really easy to do and lots of info online about it. You'll then need some way of controlling this from your phone. I'll tell you how I do it.
Set up 1
RPi running Moode Audio, controlled by Bubble UPnP app on android phone
Moode can't handle Tidal (or Qobuz, which is what I use) on its own. This means that I set Moode as a UPnP renderer. I then control this with the Bubble UpnP app. All sounds complicated but it's not.
Set up 2
RPi running Volumio, controlled by MyVolumio user interface
handle Tidal (and Qobuz) but there is a small charge for this (I pay £2.78 GBP a month)
Obviously set up 1 is cheapest (there's no additional cost other than the Qobuz subscription). Neither option requires a Roon-type Core and both options allow streaming of locally stored files from an attached USB flash drive.
Here's the key issue and one where I can't speak from personal experience. As far as I'm aware, to play an MQA file as an MQA file, your D90 needs to get a bitpefect MQA file from the RPi.
If I was going down the RPi route I'd experiment with the following set up:
RPi running Moode Audio, configured as a UPnP renderer and with volume control disabled. I'd then use Mconnect Android app as the UPnP controller, sign in with Tidal and that should do everything that you need.
Instead of Moode you could use Volumio. You could either use this a UPnP renderer or (as in set up 2 above) you could pay the MyVolumio subscription. If you pay for MyVolumio you wouldn't need Mconnect Android app as MyVolumio allows you to sign in to Tidal on the MyVolumio User Interface.
Again, all of this sounds complicated, but it's not. People are here on this forum to help.
HOWEVER!!!! There is a much easier alternative, but this only works if you're happy to physically plug your phone into your DAC using a USB cable. You could then use USB Audio Player Pro Android app. This handles MQA and no additional hardware is needed. I used to use this in my main set up, but now prefer an RPi as it doesn't physically tie me (well, the phone) to the DAC.
might be able to answer whether or not the bitperfect UPnP streaming option works as he's in on this discussion and uses MQA