Небо, заполненное наблюдающими (за тобой) вещами и голубыми облаками.

У меня в особенности было затруднительно с переводом фразы "watching things" в данном контексте, но может быть это еще можно перевести как: Широкий небосвод, смотрящий на ситуацию и низкие голубые облака. (если делать более лит. перевод) Потому что things можно перевести, как " обстоятельство, случай, факт; ситуация, положение дел вещь, нечто"
Но все равно спасибо за ваш вариант тоже)

This makes no sense to me. It's not a sentence because there's no verb. And WATCHING THINGS is a strange construction. Can you provide more context?

Earlier, by a week, he dreamed of her and not for the first time. How could it be the first time? How could he have gone for all those years without being visited by her in his subconscious?

He read once that we sent ourselves the dreams we want most. It is logical, then, that his dreams of Prairie contain more animosity than forgiveness. He knows how to be cold with himself, how to say, well, it must be what I deserve in her eyes. A kind of cauterization, to not allow himself the pain of pining. To keep it in a glass cage, so to speak.

But in this dream, she is drowning. He rescues her, pushing air into her lungs with his mouth. The sky full of watching things and low blue clouds.

She touches him tenderly, like she never would in real life. “I am made from the bloodiest part of a god,” she says. And he wakes up.

Ok, he literally means that in his dream, there are things/beings in the sky watching them.

This “sentence” should have been joined to the previous one with a comma as a descriptive phrase.

Он спасает её, проводя искусственное дыхание/дыханием «рот в рот», под небом, сплошь усеянным наблюдающими за ними существами и низкими голубыми облаками.