To be brutally honest (as if not already), Doppler makes me wonder why not simply focus on building on-top of open solutions like Vault. Considering there is no on-prem version of Doppler, you could essentially run Vault behind the scenes and provide the experience you are aiming to deliver with Doppler, giving you a marketing strategy for free ("Ready to run secret management with a focus on usability; the fastest zero to production option for 'Enterprise' secret management"), that doesn't require contrasting yourself ("We ARE Vault; it's a great tool, we made it easier"), and could even value-add or contribute back upstream (vs trying to cannibalize someone who could be your peer), and even reduces your engineering effort and the need to revalidate all the security primitives (and have 3rd parties do that for you just by their using it).
Disclaimer; I have nothing to do with HashiCorp, they've just done right by me, have been great to the community, and are always improving and learning from their mistakes. A nerve is struck when marketing tells people that they are using the wrong tool (without backing that up with data), and making comparisons to a protocol which has fallen to the wayside aside from limited use cases but otherwise is predominantly insecure.
Disclaimer; I have nothing to do with HashiCorp, they've just done right by me, have been great to the community, and are always improving and learning from their mistakes. A nerve is struck when marketing tells people that they are using the wrong tool (without backing that up with data), and making comparisons to a protocol which has fallen to the wayside aside from limited use cases but otherwise is predominantly insecure.