I will try to answer your question as I took a similar leap.
Firstly, relevancy is subjective. You can still survive in PM world without an MBA. Some people face friction while job switches. If you aren’t, you know it’s not a blocker for you. Having said all this, 6 yrs is not at all late for an MBA. International MBAs usually consider 4-6 yoe as sweet spot.
Second, yea you can learn many things taught in MBA from external resources. The unfortunate part is - How will that be reflected in your profile? One of our MBA profs used to use “MBA as a peacock feathers” analogy. In real world, projection helps, don’t we all gets biased with polished marketing, value addition campaigns.
To me, yes, MBA changed lots of thought process for me. I used to think vertically in my engineering domain, now I can think horizontally (and vertically) across domains which is a super power in functional domains like Product, Consulting.
For financial aid - Internet is filled with this information. To start with, try looking for Insead scholarships, IIMA offers some schols in 1-yr MBA, ISB also offers partial scholarships.