I'm using the Montery's Garden Insect Spray on my houseplants to get rid of a thrips issue and cant' seem to find whether I could use the concentrate in a soil drench solution or not. I also saw sites mentioning spinosad granules but I can't seem to find those in the US.

Can I go ahead and use the same solution as a soil soak (ratios according to instructions)?
Any recommendations on where to find granules if not?

Note: I know the instructions don't mention houseplants for use but from what I read it seems ok. I tested on a leaf and took my plants outside to spray/dry etc. Thank you!

I don't know about houseplants but I've used liquid Spinosad diluted in water as a soil drench in my garden many times with no problems. Captain Jack's makes it in dust and granules or you can get Sluggo Plus in granules which is iron phosphate and spinosad.
https://captainjacks.com/produ...
https://www.homedepot.com/p/Mo...