How can I convert my legacy animations to DOTs without the need for recreating from scratch?

I have a few character prefabs with legacy animations and I want to have thousands of them at runtime without any frame rate drop or any type of bottleneck.
I am creating an RTS game.
I realized most of CPU cycles are processing animation, and frame rate drops from 60 to below 25 frames per second when I have 100 characters in my scene and below 5 frames per second when I have 1000 characters in the scene.
I want my game to handle up to 1 million characters in one scene.
I want to make with DOTs because it's fully multithreaded and data oriented so it reduces data calling from RAM and can use all of CPU cores no matter if you have a dual core laptop or a 1 million core supercomputer.
My characters are low poly (but realistic and not too much low poly so it won't look like cartoon characters) and animations are 30 frames per second.
Each character has between 10 to 200 animation clips attached to it depending on character type and animations are called via C# scripts.
I use Unity 2019.4.34 LTS and can not change it because I get errors in other versions.
Update : I removed navmesh agents and replaced it with AStar pathfinding and now I get 32 frames per second when I have 200 characters in my scene and 5 frames per second when I have 8000 characters in my scene. I must get 60 frames per second at least for 10,000 characters. I haven't included DOTS yet. Please help me converting all of these legacy animations to DOTS animations. Thank you very much.