Don't expect the companies to pay. You can not force them to pay. It's a project with a MIT license. (Perhaps this is obvious for you, but a few days ago someone posted a rant by another developer because some companies were using his MIT-license project and only making a $500 annual money contribution.)
I think one possibility is to write blog post about examples of using the project to solve interesting problems. It's important that they are interesting to get traction here and in other platforms. At the bottom, add a remake explaining that you are the main developer of the project and you'd like sponsors. (I can't guaranty that this will work.)
Also, this helps as an extended documentation of the project and to get more traffic from google and to get more users. All of that can help to increase the user base and hopefully find an sponsor. (I can't guaranty that this will work.)