Removing sd-event from the library requires removing the following from the sd-bus API:

int sd_bus_attach_event(sd_bus *bus, sd_event *e, int priority);
int sd_bus_detach_event(sd_bus *bus);
sd_event *sd_bus_get_event(sd_bus *bus);

Note that integration with event loops is done primarily through int sd_bus_get_fd(sd_bus *bs). What is lost is the ability to tightly integrate with an external sd_event instance, which I consider out of scope anyway.

sd_event would initially still be used internally, but could probably be replaced with a simple poll.