Maybe try this plugin?
This can convert AnimtedSprite's animation frames in an AnimationPlayer.
GitHub - poohcom1/godot-animated-sprite-2-player: A Godot addon to convert animated sprite frames to animations in an animation player.
A Godot addon to convert animated sprite frames to animations in an animation player. - poohcom1/godot-animated-sprite-2-player
GitHub (github.com)