Rawr ow0)r

Isekai mc as non humanoid monsters on just non humanoids in general tend to be nice experiences for me and probably many others due to the fact that most of the time when a character turns into a non humanoid creature their first major goal is to become humanoid ,usually through gaining a human for, and their more unique trait of being an entirely different being is made an after thought as the character tends to stay in their human for more often than not. This idea can be popular like all things and an example of this on this site is "Chrysalis" which I've been reading for about a year now...

Another way you could do this without the isekai part of a character is to just not make it an isekai and have the most likely animal character only have an internal monologue with themselves and can only communicate with their own species or telepaths.

Anyways if you wana try something new that's not really done a lot try writing about a non human character and experiment with it to see what you like about it and what you don't like maybe you don't like this idea. :)