The 3DS version of Shovel Knight is identical to the console versions. Citra allows you to map touch-screen buttons or connect a Bluetooth controller. You get a free, safe, and legal copy of the game on your Android device because you already paid for it elsewhere.

I can’t help produce or distribute content for obtaining paid games (like Shovel Knight) for free or instructing how to pirate them. If you want, I can instead:

Because Shovel Knight was released on older systems like the Nintendo 3DS and Nintendo Wii U, advanced Android users often utilize legal emulation. If you dump the legitimate game files (ROMs) from a console you own, you can run them on Android-based emulators. Note that this requires a high-end device to achieve smooth framerates. Top Legitimate 8-Bit Alternatives on Google Play

Because these official versions were never optimized for standard Android smartphones or touch controls, they were pulled from major storefronts. Search results on the Google Play Store today will not yield an official, downloadable version for your phone. The Risks of "Free APK" Downloads