The Playdate is a wonderful desktop accessory and with the announcement of the docking station, being able to change the lock screen settings would be amazing! This would really make the Playdate more personal to the user!
Ideas:
The size of the time so that it can be viewed from further away.
Add the day, month year.
Maybe even make little reminder notifications. For instance, setting up a 30 min timer when cooking food! (I have a feeling this would cause a battery drain when the lock screen should be treated as if it was sleeping) but that would be up to the user to decide.
Calendar. Linked with the users google calendar... yeah I know this is a huge stretch lol
it's worth noting in the meantime that there are some apps out and about that can do some of these functions already (at the cost of some battery life and no auto wi-fi checks, since...it's not locked; but if it's on the dock then that shouldn't be a worry anyway
Playtime (on itch.io and Catalog) is a collection of weird alarm clocks of various shapes and sizes, and plenty of 'em have D/M/Y options as well: Playdate game Playtime
...and personally I genuinely use T minus (on itch.io) as my own kitchen timer when i'm cooking, haha: T Minus by Dale Price
(Secret pro tip: purple cover = super-magnetic backside — you can stick it straight on a fridge!!)