Solo 401K, EIN, 1099s

Hello.

 

I am thinking about getting a Solo 401(k), and my understanding is that this will require me to have an FEIN. 

 

I currently do 100% 1099 contract work, and use SSN.

 

I believe I am considered a sole proprietor - I have no employees, and do all the work myself.  I file joint annual tax returns with my spouse whose income all comes from his employer on a W-2.

 

My hang up here is the FEIN. 

 

If I generate an FEIN through the IRS,  would I then need to issue myself (to my SSN) a 1099-NEC from my FEIN? 

 

How does switching from SSN to FEIN change my annual tax process?

 

Thank you so much for helping get me started.