Concept: In-dash Techstream

So i currently have a T-Mobile SyncUp Drive device hooked up to my 2016 Prius C-2; it connects to the odb2 port and tracks my car, provides a wifi hotspot, and reports DTC codes as they are reported. I chose this over other apps like Dr. Prius and somewhat regret it, and I initially started looking into changing my setup with a cable that would allow my SyncUp to use a usb connection instead of odb2 (available on amazon) and using dr. Prius and one of the odb2 dongles they recommend. This way I would get more advanced info than the syncup provides, and still keep its hotspot/tracking features. However I got to thinking, and It seems to me that with a (most likely custom) head unit that is SBC or NUC based, and the proper connectors, it is not all that difficult to build an in dash computer system that would not only be huge upgrade from the POS stock radio, having for instance: apple music/spotify/pandora/etc built in, broader media file support, extremely upgradeable and customizable - it would literally be a desktop PC in the dash; a dashtop if you will. A dashtop could very easily run techstream and thus be a complete on board diagnostic system; the system requirements for the software are very basic and it is is not hard to obtain SBCs/NUCs that fulfill them. Once I finish the whole thing I will do a writeup on how to build one, but i have several questions: can techstream be connected and used “live” during normal day to day operation of the vehicle? For instance does it give readings in real time like the dr. Prius app provides? Or does techstream require maintenance mode to be active? If so then it is still possible, it is as simple as modding an odb splitter - yes i know they are BS and only one connection is allowed at a time, but by adding a switch that changes the active connection from the dr prius dongle to the techstream dongle upon activating maintenance mode solves this issue, and this sesign may actually be the better option, regardless of techstreams abilities. I have the basic design outlined, and know that it could work, based on my experience building computers and crafting diy electronics mods, for me the only wild card is techstream as I have yet to use it myself. If anyone has any suggestions on how to pull this off I welcome your input, and to those that say it cant be done or it will never work, just sit down and shut up, the fact that head units built from a Raspberry Pi exist is proof that one could be built using a windows compatible board. The only precaution to take into account is the total voltage, but as long as powering such a system is less than or equal to the power draw of the factory headunit (+ the usb cord/aux connection above the glovebox - they wont be needed with a dashtop and so the voltage powering them can be rerouted to power the dashtop if need be)