Yep all in this together. One thing I am thankful for is there is a lot of focus and resources on MND/ALS and there is a community out there for support.
An easy "test for autoimmune" is they can always trial you like me on the drug and just be careful, these med also suck and only trial to see if it provides some benefit (unlikely). The result of the NFL itself is suggestive it ain't autoimmune too and what's important isn't so much the actual >20 value but actually the trend - meaning you'll get a repeat. For me mine doubled in 9 months.
The EMG you had wasn't SFEMG - If you read the EMG - it mentions it was a "normal" needle - the SFEMG basically isolates pairs and it's a very specific needle type/test and in my case 1.5 hours of multiple docs poking my eyebrow, and getting very excited to find stuff (which was mildly entertaining i guess). I think the point to tell the neuro docs is getting another datapoint on LMN signs and if it's bulbar - SFEMG may be more sensitive to that. The neurologist who saw me at the muscle clinic knew what I had from right from the start and I trust what they have found given it lines up with everything.
I wouldn't discourage you (or anyone) to drive the 2nd opinions, but I would also suggest, you may get to a point, like me, where it's like - is it really that important to keep digging vs just living life - knowing the care team around me and just "keep moving forward" (ignore the fact that's my FTD "talking"). The distinction on MND (PLS) vs full ALS will happen anyway over time, clinically they saw the UMN part and the LMN symptoms are there, the EMGs just codify what they already saw clinically (and is further documentation).
Last point, Voice Banking - do it now, I waited a bit to long and relied on them reconstructing from voicemails, videos etc...
Prayers and happy thoughts.