There's a way that works for many terrestrial orchids and a few epiphytes known as the cardboard method. It involves soaking cardboard for a week or two in rainwater and then incorporating it into a mix of substrate suitable for the species you're working with. Here's a pic of some grass pink orchids, Calopogon tuberosus that I sowed last fall with the method. Note the piece of dead leaf in the center of the pic. The red spot is a corm starting to develop, which will be necessary to get the plant through its upcoming dormancy this winter:

I’m wondering a few things. From this loose procedure it seems there is no added sugar or nutrients to supplement the embryos? Was the picture plant the entire yield of a single pod?

Without added nutrients, asymbiotic propagation isn’t feasible in nearly all situations. There are a few genus that have larger endosperm, or may be not be as species obligate with fungi, but that is very far and few between. Prior to Knudsen seed used to be sown underneath the wild collected mother plant, limited germination would often occur. For the hundreds of thousands of viable seeds, this isn’t really what I’d call a success.

That said, I do know that we can improve yield of seedlings by re-examining the proceed to eliminate the disturbances to the seedings, as well the headaches and inefficiencies of having to replace. Challenges to address would be A) equidistant spacing of viable see to allow equal access to light and nutrients, preventing protocorm clumps B) a innate inorganic surface, potentially with antibac and antifungal properties C) liquid medium that allows replenishment.

Incorporation of proper air flow, including CO2 supplementation , would also be of great benefit. While these things would “get us out of the lab” so to speak, they would improve yield and variation of seedling population.