Blaxel & E2B use microVMs which is usually the standard for this kind of worloads. E2B feels more ephemeral while Blaxel feels more stateful, depends on what you're looking for. Daytona uses containers, less secure than VMs.

I heard Vercel & Cloudflare launched a sandboxes offering too. Haven't tried it yet but i'm naturally wary of the marketing fluff around their annoucements