Seeking Self-Serve Access to Google DV360 Without High Fees - Have Info on TTD and Amazon DSP

I'm on the lookout for a platform that provides self-serve programmatic ads with no minimum spend for Google DV360, without those hefty $1K/month fees. I have solid sources for similar services on The Trade Desk (TTD) and Amazon DSP, and I'm willing to share this information. I specifically need this to access programmatic guaranteed inventory on YouTube via DV360. If anyone can provide a lead, I'd greatly appreciate it. I've searched extensively online and made countless calls, only to hit dead ends where 'no minimum' actually meant hidden high monthly costs. Looking forward to any tips or connections!