Practical testing …
Laying the cables in the case is easy with a fair amount of skill. For ITX cases, it would definitely be worthwhile to buy prefabricated cables for the power supply that are adapted to the case. Otherwise, it looks like everything fits into the ITX case, but it is very difficult to lay the cables cleanly.
At this point, a big thank you to Biostar for providing the Biostar X470N ITX motherboard!
We were able to comfortably fit this Biostar X470NH ITX motherboard for AMD Ryzen processors into the Lian Li Q58 case.
A graphics card can be installed up to a length of 320mm. A Sapphire R9 390X Nitro+ fits well in the Lian Li Q58 and there is even a little space left.
The NZXT Kraken X53 AiO water cooling was used in the lid here.
Here there is also the second compromise, because if you want to install a 280mm AIO, it must be mounted in pull instead of push mode, i.e. the fan would have to be upwards, because otherwise it would not fit. In addition, you might have to remove the SSD’s HotSwap cage when using a somewhat thicker AIO or radiator.
The front can be removed very easily, which is necessary to remove the SSD HotSwap cage, for example.
If you follow the manual during installation, you will be rewarded with a speedy assembly. Otherwise, it can happen that you have to remove and install parts several times. However, since the manual is very detailed and comprehensive, this should not be a problem.
And since RGB makes everything even prettier, you can see all the (A-)RGB illuminated components very nicely 
Lian Li Q58 Result and general impression …