Your system information

• Steam client version (build number or date): 2020-01-25
• Distribution (e.g. Ubuntu): Ubuntu 18.04.3
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Ubuntu's Gnome is set up so the screen will lock after a period of inactivity and require a password. So far, so good. When I'd like to stream a game to the living room, I've almost always been away from the host long enough for the screen to have locked.
What happens when I start a Remote Play session then depends on the game (or rather, I suspect, capture method), a bit, but usually the game will display fine on the client, even though the host is displaying the lock screen / password entry screen, but it won't accept any input, because that is all going to the lock screen / password entry screen.

Issues:

• It's not obvious on the client what's happening and why input doesn't work.
• Entering the password blind does work, but is fiddly and error prone, also it doesn't feel right from a security perspective -- who knows where it's going.
• It's even more of a hassle on mobile devices.

Possible[?] improvements:

• Leave the screen locked and stream out from under the curtain (if it's possible to override the exclusive input-grabbing and doesn't have a performance impact).
• Unlock the screen host-side without requiring local user input (if that's possible).
• Stream the lock screen, so the user can see what's happening and enter their password as usual.
• Provide a client-side method for password-entry, like a pop-up window, and use that to unlock the screen.
• Detect that the host's not receiving input and suggest that the screen may be locked.