So nothing really has changed!
Mixes need to be on point in the basic midrange area. That means it should come across on a portable cassette machine or a modern phone! That gets you in the door. The mix should ideally have full fidelity when played on a suitable device. You can get away with a release that doesn't, you just won't (hopefully) win any awards. Same as is ever was.
Any notions that crop up of purposefully mixing for rogue shit devices are out to lunch as always. You might be able to craft something that works out in left field but then the people with shit devices that are in right field are left out. Oh, and the ones in left field didn't even notice the effort! Turns out they're used to their left field device and fine with it.
Make the main human hearing midrange elements on point and even someone with a shitbar will at least be able to hear it (normal to them) and sing along.
Yeah, lots of excuses for damaged or novelty sources on these streaming platforms.