I didn't add in my whole Bio in the original message for brevity's sake, but have also been a paramedic for nearly 20 years now, and am on a FEMA Urban Search & Rescue team as a paramedic. I can easily transition into a physician position on the team once I have my medical license. I think part of what is also pushing me towards the anesthesia route vs peds-> PICU is that if I do anesthesia, it keeps me "relevant" to adult care, as I hope to continue my work with the USAR team as a physician. I totally understand, however, that in order to make this truly relevant, that I cannot limit my practice as an anesthesiologist to just pediatrics. I was told by numerous people that to maintain relevancy in EMS/pre-hospital/disaster medicine that the best way to do that is through an EM residency, but I am just not interested in EM as my career path for numerous reasons.
Yes, the adult portion of pre-hospital stuff is important, although Pediatric transport medicine is woefully under-researched (my scholarly activity while a PICU fellow was related to Peds transport medicine). That specific role of Medical Director likely needs the adult care portion, particularly going forward 5 or 10 years down the road. There is a niche for Peds people in disaster medicine and larger pre-hospital systems though. You certainly have a path forward that would be desirable to PICU fellowships once you start you interviews.
Now that EMS is an actual accredited fellowship, it seems like it's made a huge jump in terms of how EM dominated it is. Even though the fellowship is open to anyone who has completed any ACGME approved residency, the training programs are being run almost entirely by Adult EM folks and because it's new, small, and generally unfunded (a few rare places have funding in place, but most are having EM people do shifts in the ED to generate revenue to cover the costs of the training program and their stipend), it's added an additional barrier for non-EM people to get into the field. I had looked into doing after my PICU fellowship and while most were excited to talk to me, in the end the funding issues killed any chance of going forward.
Not to muddy the waters even further for you... but all that said, since you're tacking on years of training at this point, you might consider the EMS fellowship as it's only an extra year. If you really foresee the FEMA team as your destination, you likely would be totally fine with only the extra EMS year after a PICU fellowship as the EMS board certification is the most relevant/proximal training to that position. But if you want the OR time, it goes without saying you need the anesthesia training
I didn't come to realize the EMS fellowship existed until 3rd year of fellowship and based on life circumstances, it was really difficult bypass going to that first attending job when the funding issues started to really show themselves. With a 3 year headstart especially if you were at a place that had an EMS fellowship, you likely could form connections with the powers that be, get a plan in place for an EMS fellowship and figure out the funding issues ahead of time. Doing anesthesia might make the funding issues easier to navigate as well, if you could convince the business offices to work out some way for your anesthesia revenue to get into the EMS fellowship coffers. Given that most PICU's are in financially distinct hospitals than the adult EM programs, it's probably impossible to get PICU shifts or even Peds ED/UC shifts to funnel money towards the fellowship, whereas adult anesthesia shifts would have fewer moving parts. You might also explore offering to EMS programs doing the fellowship as an unpaid fellow and then moonlighting where possible. Still doesn't solve all of the funding issues but saves the programs some costs that they might be amenable to.
Of course, in 4+ years from now, perhaps more of the EMS programs will have funding and this will all be moot.