I would personally be using the greensand if you plan on using this soil for a bit. I'm no expert but I remember reading that the only major drawback to using it is how long it takes to breakdown and become available in the soil. No sources, just drawing from old posts I remember reading, but essentially it's just another mineral/rock dust input with a unique nutrient profile. I like the idea of a more well rounded mineral profile than something like langbeinite. Never used langbeinite but 0-0-22 seems easier to overdue than greensand at 0-0-3. I've been using greensand in the worm bins and when re amending my soils for a little while now. Hopefully someone else can be a little more specific with sources or more experience, just my thoughts.
I used biolive and the vegan blends from down to earth on a bunch of soil for some comfrey plants I started last year. Used two different bagged compost, peat and rice hulls for the base. Added a little extra alfalfa/kelp/basalt to the 50/50 mix of biolive and vegan blends. Filled 15x 20 gallon pots with this mix and all plants are healthy and thriving with zero maintenance other than watering a little between rainy days. Reminds me I need to hack them down soon and get my compost piles up to speed again.
My main suggestion would be to try and source some quality compost/ewc first. In my opinion that will give you the easiest path to success, especially when starting a fresh batch. The microbes are essentially the heart of the soil, so starting with a healthy diversity will only make things kick into gear that much quicker.
Sorry for rambling, just my thoughts. Hope everything goes well with whatever route you go.