When the power is off chances are that whatever is integrated is degraded anyway. And for actuators just choose some that fail gracefully and allow manual handling. For the rest use HA as much as possible, favour local integrations with no cloud dependencies… and when there are dependencies than make sure the override is available physically (looking at my vaillant HP). Then stack UPSes or even better home grade batteries (my next endeavour) and have backup connectivity to internet and you’re a peachy as can be.