Yeah, but the problem there is that when the MicroSD is used in an SD adapter, the speed DROPS, as it has to re-route through another connection. The Golden Rule of computers is that the shorter the distance, the better it works.
Which is usually why I frown upon adapters, daisy chains, and long USB cords. I've actually solved problems removing those issues. I've had issues where the drive wouldn't read with a long USB cord, where drives were having slowdown on daisy chains, and where SD cards were fast by themselves, but slower in the adapter.
Been repairing and tech supporting for over ten years. You'd be amazed what you run into
Best I can tell you is get a SD card for EmuNAND if you're using it on a 3DS and a MicroSD card if using on a N3DS.
Also, don't worry about future proofing as prices ALWAYS go down on storage. That 64GB card you'd pay $60 for now, will be only $40 six months from now. As storage goes up, prices drop.
I remember paying $150 for a 2TB drive last year. This year, I only paid $89 for it.