Bletillas can grow in pots but since they spread, you need to increase the size of the pot each year by about 100%. They need forest loam, with some extra woodchips and ground leaves mixed in. I grow a ton of them and they are very easy if you keep them in the shade, keep their roots cool and don't let them get real dry.

Here's a pic of one little specimen of mine.
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Lainey

The answer is yes but combine all your listed ingredients!
I am testing what I call Debris Mix on Pleione, Bletilla, and Epipactis species. So far all seem to be doing ok.
I have the Pleione and the Bletilla crowded into small net pots and/or 4" square plastic pots. I have flowered them but the slugs got the flowers before I could get a good image!! the Epipactis is in a one gallon regular pot as I
repotted when they started growing this year. All look good and the E. gigantea is in flower.
You should water with good quality water. I use r/o water.
Also fertilize when in growth-I use liquid MiracleGro as it has a formula of 12-4-8 which is good for growth and will not burn and can be used frequently (I am rather haphazard about feeding-it happens when I remember!!).

Flowers look very nice.