Yeah, I'm not sure. There's room, but I'd really have to cut away the rear for it.
A single-slot card would be much better, but those are in extremely short supply so it'd require modding a dual-slot card, but then at that point why not just let those people mod the case?
It's fun to think about the possibilities of such support, but how many people would actually use it? And how many people are interested in the case as it is for that matter?
If you wanna bring up the case on the market, you need to define a targetgroup. A single slot card is not usefull because single slot cards and low profile cards works on the same level (GTX 1050 Ti or RX 460 - so low/medium level).
The second question is would all like the solution of the psu with dcdc board and no standart sfx or atx psu ?
In my opinion is your case nice for HTPC with medium gaming options.