So i tried this mod.
And it is alittle broken (havent left nauvis yet on this save file).

First of download:https://mods.factorio.com/mod/QualityAssurance?from=search
This mod unlocks all quality from beginning, or you will brick your factory when you reach first stage of quality.
Before you unlock quality games play as normal. As soon as you research quality (up to rare first). Everything will try start making rare items.
This means even ore. So you will end up deadlocked everywere if you dont purge everything on belts and change reciepe to rare materials.
And it will happen again when you unlock epic and legendary quality.

second problem was trigger research. Like mine uranium. Game needs normal uranium to trigger this research and you get only legendary.
I used a console command to get around this. This will happen with more trigger research.

Third problem is launching rockets. Rockets will not accept (or im doing something wrong) legendary quality materials to build a rocket.
And everything you craft/mine is legendary.
This mod: https://mods.factorio.com/mod/Dequalitier?from=search
I could build this using my old base (the one deadlocked since i just abandon it). So i could build this box in normal quality. Dont think you cant build this if you have all quality unlocked. That brings me to fourth problem.

fourth problem.
You cant hand craft anything. Or mine somethings by hand to get "normal" quality. This is needed. Or get an option to craft at any quality you want/need.

5th problem:
To use any blueprints, you will need to get familiar with upgrade planner.

Problem no.6:
If you build a space platform or spaceship using a blueprint. You cant use upgrade tool to upgrade spaceplatform to legendary (or i couldnt figure it out).
So i had to dequalify space platforms using the mod in 3rd problem.
If you using starter kit for space platforms with legendary quality it will brick blueprints using circuits (green and red wires to communicate).
I just used the mod from 3rd problem to dequalify starter kits and it worked. But beware allmost all spaceships/platforms will use "normal" or green quality on things. So you will have to setup spaceships and platforms so they work with legendary quality stuff.

This is the problems so far i have stumbled on. Tonight i will leave for vulcanous. And lets see what problem we can find there :)

Love the mod tho! Some touch ups and it will be a solid mod!

Sorry for the bad english. English isnt my first language.

I have just hit all the same problems. I managed to get around the Uranium research by saving, loading without the mod, then reloading again with the mod enabled. Loading rockets is a harder problem, thanks umpabumpa for the Dequalitier mod suggestion.

I'm not too fussed about 4th and 5th problems - they seem like OK trade offs for playing a full game of everything-legendary. A mod-option that makes everything hand-crafted to be legendary would be fantastic though.

I'd like to add one more suggestion to allow chopped down trees to count as legendary wood. Making early game power poles without legendary wood is impossible currently.

Dunlace, if you open source the mod I would be happy to contribute as I am also a developer! This is a neat mod to play Factorio at its upper limit and I'm surprised that it's one of a kind.

As someone who also wanted to play with higher quality from the start (after all that's why am i restricted to gambling with LOW % for a dlc I paid to have access?), I want to recomend: Steeper Quality

After failing with the mod for the reasons you 2 mentioned, and let me not even start with not being able to launch the rocket, I tryed Steeper Quality mod. I asked the modder if they can add the ability to change the value for uncommon items. And this was done. Aka, you don't even need Uncomon, rare, Epic, or even legendary. You just change in mod's setting, what rank normal items to be. Exemple, if you put 5, then ALL Normal (uncomon) item will have the values of Legendary! <- warning, this does apply to enemies as well. But it should be so dificult. Plus, the mod dosen't remove quality, aka you can still set a value, don't know, let's say 10 (legendary is 5), to weapons and they will be way OP so that even legendary stat normal enemies won't stand a chance.