Pencil2d and Clipnote studio. You can find Pencil2d’s download on their website, however Clipnote is on itch.io and is similar to flipnote, which you can find on older 3ds, but for PC, just use clipnote.
Also, Flipnote was used by raxdflipnote to make the infamous LETS GO GAMBLING meme. Clipnote has the same artstyle, and if you want to export your animations, there is a plugin named paperclip that allows you to do that.