While the Doom stuff seems like it's kinda soulless attempts at e-cred, this is more interesting because 1) it's an old/historical product (SuperCard DSTWO) that was actually in use rather than something someone made recently and 2) it was made with functionality in mind rather than showing off for the sake of it. Specifically it allowed SNES and I think GBA emulation on a system that would normally be way too weak for it. I remember hearing the chip in this flashcart was roughly equivalent to a PSP. I had one back in the 2010s and it remained useful even with a 3DS as for years you couldn't run DS games off the SD card on 3DS, and I think trying to emulate SNES/GBA on 3DS was also not great. Later on this flash cart became less desirable than the more basic DS-only ones because it had a big power draw even when not being actively played (IIRC), so if you left it in your 3DS and played digital 3DS games it was an extra drain.
I will agree, though, with the general Doom sentiment as well as the clickbait title. Seeing the description say it was the SuperCard DSTWO restored my faith.
These days with TWiLightMenu, a DSi or 3DS doesn't have much use for this flashcart, or any other, but it remains useful for a DS Phat/Lite.