mixtere Hello, welcome to the Spine Forum!
First of all, I have no doubt that what you want to do can be done with Spine. Of course you will need time to learn, but the advantage of using a digital animation tool is that it is very easy to redo and adjust later. Animating with a physical puppet may be quick and easy at first, but if you want to fix or modify something you did wrong or notice some improvements, it would be harder to redo or adjust the animation. I think it is a very good choice to use an animation tool like Spine, which is easy to redo, to make sure that the work is satisfactory.
Now, for the sake of clarity, I'm going to break down each of the things you want to do and how you can make them happen:
Having the mouth move to match an audio track:
Spine can play audio files within the editor, making it possible to create movements that match the audio. There is also a view where you can see the waveforms as described in the following page of the User's Guide: https://esotericsoftware.com/spine-audio-view
However, there is no lip-sync function in the editor to automatically create animations to match the audio, but instead external tools created by a user can be used:
DanielSWolf/rhubarb-lip-syncblob/master/extras/EsotericSoftwareSpine/README.adoc
Move arms, legs:
Of course you can do this with Spine. Spine has the advantage of IK constraints, which allow you to fix the legs and arms in specific positions so that they appear to be in perfect contact with the floor or wall. The following Raptor example description page may help you understand how the skeleton can be moved.
https://esotericsoftware.com/spine-examples-raptor
Output the animation as a video:
You can export the animation in AVI, MOV, or WEBM format. Each can be exported including audio.
If you have any questions, you can always ask them in this Spine forum. Basic questions about the editor will be answered within 24 hours in most cases.
