About six months after release, Returnal is finally getting an option to save your game mid-run.

https://blog.playstation.com/2021/10/26/returnal-2-0-update-brings-suspend-cycle-and-photo-mode/

One of the main features of this update is the Suspend Cycle functionality, which will allow you to pause your cycle to be continued later, letting you exit the game and turn off your console without losing your progress in that session. The structure of the game remains unchanged, so this functionality is not a traditional mid-game “Save Game” option: by suspending the cycle, Returnal will simply create a single use suspend point, and once you resume playing the suspend point is deleted and cannot be used again. Your game will continue directly from the moment you left it, and if you want to suspend the cycle again, your progress will be captured from that new point onwards. There are some limitations in place – for example, players won’t be able to create a suspend point during Boss battles, cinematics, first-person sequences or during intense combat scenarios – as we felt there are certain moments in Returnal that are best experienced unfragmented to preserve the intended challenge and flow.

Since I've already finished both of the endings, a save feature and photo mode alone aren't enough to bring me back, but I do hope that this addition will inspire some folks to finally pick up the game.

Hooray! I may give this game a shot now. I made it an hour or so in and enjoyed it well-enough, and then lost my progress to the PS5 rest mode issue. After that, I never returned to the game :|