I imagine many providers have some level of implicit failover. Have you confirmed with DO what level of failover they provide with a droplet?
As an aside I’ve been running two forums on Scaleway for several years and had maybe 30 mins of downtime not caused by a deliberate rebuild? Can only imagine DO has similar robustness. Why do you need to improve on that kind of SLA? That’s a better level of robustness than most banking systems I’ve known!