The cable lengths in the Dan A4 are all going to depend on what your setup is, unfortunately I don't think you can standardize it.
What PSU are you using, a SFX or SFX-L. Some PSUs require sense wires while others do not.
Are you going to put a radiator under the PSU : You'll need unsleeved cables if you do.
What is your motherboard layout
What is your GPU
I just purchased my Dan A4 to put a Strix 450i + Ryzen 3600 (air cooled) in along with a Corsair 650 platinum and a 5700xt. I will try and report back on what the lengths of my particular setup should be.
I disagree.
While I do agree with you that there are valuables in every system, the case is still the same size as everyone elses. Hence for motherboards etc, sure the connectors can be placed differently, yet it's an ITX board. There aren't that much space on the board itself and not that many "odd" ones out there.
Are you going to put a radiator under the PSU : You'll need unsleeved cables if you do. - No you don't. I have a Asetek 645LT and I've used the included sleeved cables that come with the SF750 and it worked.
This person has custom ones for the Dan A4 and I've used the 8 pin CPU, 1x 6 PCIE and 1x 8 PCIE as well as an 24 pin, and they all fit perfectly. Keeping in mind I use the ASUS X470-I Gaming motherboard: https://www.pslatecustoms.com/collections/dan-a4-sfx