Bento Buddy is a Blender add-on with extensive features for character manipulation, animation, retargeting and conversion.
The extensive list of features have been provided in tutorial fashion. Have a look at this list of over 500 Bento Buddy specific videos.

This tool was designed for Second Life(R) in mind but it grew beyond that. Of course OSGrid/Opensimulator are also supported.

Bento Buddy is a full replacement for other rigging/skinning tools for SL content creation. All of your popular devkits are supported for any mesh body and I'll provide a short list here.

9s
Aesthetic
Anthro
AVIL
Core Nova
BBL
Bebe
Belleza
Cinnamon & Chai
DEVness
eBody
Hoist
Inithium Kario
Kalhene
Kupra
Kuro
LeeLu
Legacy
Maitreya
Meshmerized
Orange Nova
Original Industries
Rebirth
SelinA
Senra - Linden Lab®
Signature
SKING
SLink
Spider Productions
Star Mesh Body
Super Mesh Brothers (SMB)
ToddleDoo and TweeneeDoo
Tonic
uLukie
Utilizator
Zooby
... and more.

The included Character Converter can bring content from any source into Second Life(R), and target other engines. Some of the maps that perform this duty are shown below, and you can create your own using the Visual Snap Mapper...

Cascadeur
Character Creator 3
Character Creator 4
DAZ, Gen 2, 3, 8 and 9
Deep Motion
Human Generator
Makehuman
Manuel Bastioni Lab (MBLAB)
Miku Miku Dance (MMD)
Mixamo
Plask
Ready Player Me
Rigify
Rokoko
Sansar
Sims, 3/4
Unity
Unreal Engine 4/5
Vroid Studio
XNA
... with the snap mapper you can convert anything.

These maps are also responsible for retargeting animations. If it moves you can bring it!