Yea unity doesn't have any native 3d bone weight editor but all meshes have a bone weight array so you can (through code) set the weight of each vertex. If you had C# knowledge you could probably make a tool to paint bone weights easily, or if you have the cash you can buy assets for it
https://assetstore.unity.com/packages/tools/animation/puppet3d-111554Basically all the things that most models support (animations, uv wrapping, bone weight, skeletons, dope sheet) are interfaced already in unity but don't have any tools or high level access from the editor. When you import like a blender obj model all the data is unpacked and added into the mesh component, so you can change things like uvs and animations in the code.
Editor interface wise, animating is handled through one dope sheet that allows you to set the transform of objects every frame. So you can basically follow the blender workflow of adding bones and parenting limbs to each bone and then building a hierarchy of bones, moving them every frame and assigning the parented transform changes