The product shape we built at my company is similar to yours and we chose to market capability/value-add rather than "cloud". Didn't really work. I'm bearish on the "sandbox" myself, I just instantly think "either a more expensive vm, or a thing in a less expensive datacenter" (also, my personal experience suggests that people don't want to sandbox things, but there are things they want that need to have sandboxes).

I don't even think Cloudflare has a name for theirs, I remember hearing it called their developer platform but after checking just now, they seem to mostly just call it "products".

Devtools marketing to consumers feels pretty impossible to me. I think you either need to be absolutely massive and have existing credibility + tons of resources to throw at every possible marketing channel, or figure out how to get people to truly love your product/brand. You're basically selling trust/professional identities in most cases rather than compute or APIs.

If I were to do it again I would either pick a different vertical or put 90% of my effort into community-building, events, PR/tech-influencer stuff, and flashy demos. You only need to fall back to widely known framings like "cloud" when nobody knows about you.