Feel free to share any specific questions or scenarios you’re working on—I’m sure the community here would be happy to provide insights.

However, I don’t have a US-based W2 (but work full time for an American tech company in their London office). 

Hey I am an agent in Salt Lake, if you haven't already run comps feel free to reach out and I can send them over to you.

The pandemic forced people to work from home and having spaces that worked as offices became important. 

Make sure you talk to a Banker or Loan officer that is well versed in both SE (Self Employed) income and also Non/QM programs.One tip I will give you as a Banker is open up a "Business Checking account" and for the next 12 months pay "Everything" out of that account. 

Not sure how old you are, and $200K in a 401K may be a little or a lot based on age, there may be so many implications taking out money from your $401k, especially if you are still working for this company.feel free to reach out for tax advice

I can provide him with an online log in so he can review the books from his office.

An LLC is not free.

It doesn't care if it's day or night, or whether you have low voltage task lighting or office lights.

Please feel free to reach out.