I've added a ton of new mechanics（included weapon explode and wet） to this mod (mostly about muskets, blunderbusses and some new weapons ), can I upload new mods to various platforms?

Yes, you are allowed to do that - however, you need to also adhere to the MIT license: https://github.com/ThexXTURBOXx/Balkons-WeaponMod-Legacy/blob/1.21.4/LICENSE
Most importantly, your redistribution needs to include the license file in some form.

However, you are also more than welcome to create a PR to my repo and I can include most (if not all) changes and additions in the main version :)

Thank you:)