How about "shooting" the seeds at some velocity into the ground so they are embedded a few mm into the top soil?
Anecdotally, even from right next to the ground I don't think seeds have enough mass to have the kinetic energy at any realistic speed to embed into the soil.
Can we coat the seeds in a layer of compost / biodegradable fertilizer ... and so make them heavy enough to work like small bullets, and also thereby protect the seed from shattering on impact
I'm not calling bullshit, I'm honestly curious. I'd like to experiment with them - maybe using a paper or clay "sabot" that encases the seed, then fire it out of a relatively low-pressure pneumatic barrel.
I'm imagining a fixed-wing drone with a downward-facing semi-auto "seed gun" that fires seed "bullets" from a magazine. It sounds like a fun side project that touches on several of my hyperfixations :)