Quick answer: Azahar 2127.0 is in release candidate testing on GitHub. The 3DS emulator's Android version adds per-game settings, ADPF performance hints and custom GPU drivers on non-Adreno devices, and the stable release isn't out yet.
Azahar, the open-source 3DS emulator that carries on from Citra, has version 2127.0 in testing. This is a release candidate, not a stable release yet. RC1 and RC2 both went up on GitHub on Nov 6, and RC2 fixes a crash that could hit some older or lower-spec devices as soon as a game launched. The team calls 2127.0 "arguably the single largest update we have ever published."
On Android, the big one is per-game settings, which you open by long-pressing a game in the list. Azahar also now uses Android's ADPF (Android Dynamic Performance Framework) API to tell the system about bursts of CPU work. The team says that improves performance on most Android devices, and it saw a 15% boost on a Mali device. Custom GPU drivers are now allowed on non-Adreno devices too.
Notebookcheck says per-game settings are handy on dual-screen handhelds like the Retroid Pocket Duo and AYN Thor. It points out the Duo can run some lighter 3DS games at four times the resolution, but other games only at two to three times.
Changes for every platform include a new ROM Bundle format that keeps a game and its updates and DLC in one file, audio, frame and input latency cut by 1-2 frames in some cases, faster texture handling, and a new interpreter for devices without JIT that lets iPhones as old as the iPhone XS run the emulator.
The team says the release candidate period should ideally last 7 days, longer if major problems show up, and recommends backing up your Azahar user data before trying it. The update also resets existing shader caches, so performance can be lower for a while after moving from 2126.2 or earlier. Notebookcheck notes it isn't on the Google Play Store yet.