I agree that you have to dig in and do research, but I also think it's money well spent in potentially preventing bigger problems. We recently hired a nurse from Independent You in NoVa (my mom is in a retirement community in McLean) and she goes with my mom to doctors' appointments and sends us an after-action report.
I did the med management system for my mom but I'm local so it wasn't that hard for me to get the system set up. I put together a spreadsheet organized by category (diabetes, a skin condition, OTC), medication name (including both brand name and generic as well as which one she's taking), how many and timing for each med, the pharmacy she gets it filled from, the prescribing doctor, the last refill, etc. It was a LOT of upfront work, but now we have it under control.
She's on a real fixed income, so I comparison shopped and her pharmacy benefits manager is cheaper for brand names for the 90-day supply by mail order and her local mom-and-pop pharmacy (that delivers or sends by mail) is cheaper by others for generics. The big trick was to get her down to two pharmacies, 90-day supplies, and automatic refills wherever possible.
Both she and her visiting nurse have a copy of the spreadsheet. It really helps to take it to various doctors' appointments to make sure everyone's on the same page.
What we did for my mom is buy her 4 of these weekly pill organizers with three compartments for morning, noon, and night:
https://www.amazon.com/gp/product/B088K5YND8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
This way we can do an assembly-line loading so that she's set for a month at a time.
I also put together a "cheat sheet" with one of each pill taped to a piece of paper and labeled with the medication (including vitamins), so that she can refer to what each one looks like if necessary.
There are services like PillPack:
https://www.pillpack.com/
which might be a great option for your dad.
If your dad is still living at home, though, with only your stepmom to take care of him, it sounds like he needs more than a health care navigator. And does your stepmom have full financial and healthcare powers of attorney? Do you or a sibling? It sounds like the $h1t might hit the fan sooner rather than later.
I'm sorry. I know how overwhelming it is. My mom doesn't have dementia (please God knock wood) but she has been medically complicated and it absolutely has been overwhelming.