I think you need to read some more about water chemistry. The water chemistry (which includes pH but also alkalinity and hardness) of the water does matter a lot. Some fish, like angelfish, come from soft acidic water, but have been tank bred for so many generations that they are used to harder water, like they have in the Florida farms where many of them originate.
Cardinals are mostly wild caught still, and live in a pH somewhere in the 6s (remember pH is an algorithm of 10, there is 100x difference between a pH of 6 and a pH of 8). So no, they won't "get used to" a pH of 8 in the time it takes to drip acclimate. They won't live as long, and they may have issues with dropsy and bloating. Keeping fish that need hard water in soft water makes them prone to fungus and finrot, keeping fish that need soft water in hard water makes them prone to intestinal issues as described above.
Of course, you will have people saying that they keep cardinals in a pH of 8 and they're fine, but that is not how it generally goes. I have kept neons and cardinals together on several occasions and neons do far better, that's because they're tank bred...probably in farms not too far from where I live!
The tetras and danios you mention are overall much hardier fish and tank bred, so better choices for you.