I will keep this pretty simple. Because, well it is.
We use this mix for all seeds. We use it for pots and for soil blocks.
Vermiculite, Pearlite, and Peat Moss
Yes we use peat moss. You can use coconut coir in place of it- it at times can be hard to source and it is more expensive. We have used it in the past and still will at times- but for our bulk seed starting mix we continue to use peat.
This mix holds together well, while still allowing enough drainage and airflow for the tiny seedlings.
You can source all three of these ingredients pretty much anywhere. From Lowes to Amazon.