What can be imported from blender to other software? Freelance tips needed pls

I had my first freelance job and I am so grateful for it. Now I want to maybe try my luck to sell my services or even maybe some models on some website. The experience that I got from first job was great, I modeled a character and they were pleased about it and all.
I just modeled the character and textured it. But I want to ask is what other type of data can be imported to other software. I use blender and they used other software like unity. There is a chance that I could work with someone that works with maya or C4d etc…
Well I know that If I just model the character I just need to make it a fbx file. But I wonder, if I propose them to make a complete rig, will it be imported to other software?
I am asking because I do not want to propose more services like rigging, weight painting, animating,etc… if it doesn’t even will be imported to other software.

I am a noob in this so I need some information. Also I made some research and it wasn’t very clear.
Thank you in advance

See BlenderBobs video:

Thank you so much