Secrets -- yes, it's being tracked here: https://github.com/psviderski/uncloud/issues/75 Compose configs are already supported and can be used to inject secrets as well, but there'll be no encryption at rest there in that case, so might not be ideal for everyone.
Speaking of Swarm and your experience with it: in your opinion, is there anything that Swarm lacks or makes difficult, that tools like Uncloud could conceptually "fix"?
Regarding questions 2 and 3, the short answers are "not at the moment" and "yes, for now", here's a relevant discussion that touches on both points: https://github.com/psviderski/uncloud/discussions/94
Speaking of Swarm and your experience with it: in your opinion, is there anything that Swarm lacks or makes difficult, that tools like Uncloud could conceptually "fix"?