Being the only dev in a startup since 2 years without a single day off where I wasn't messaged by my employer I want this. At least I'll have a 3 week out of country trip where I do not bring my laptop later this year...
The only people who should suffer this much are the true busines owners.
But... That's not how days off work.
Real engineers think about handling things when stuff goes wrong, not "everything will be on the happy path forever".
Yes, there are constraints, but to me this sounds like an unacceptable level of exposure.