Add the Almanak shortcut

Or build it yourself

Open the Almanak app once first, so Shortcuts knows its actions. Then in Shortcuts:

1. Tap + to make a new shortcut. If it asks you to describe one, tap Edit to add actions yourself. Name it Almanak exactly.
2. Add If. For its condition choose Shortcut Input, then is not, and type home. (If only "has any value" shows, tap Shortcut Input and set its Type to Text.)
3. Inside it, add Almanak's Get Wallpaper for Now (leave it on Lock Screen), then Set Wallpaper Photo. Set its screens to Lock Screen only, and in its options turn off Show Preview and Crop to Subject.
4. Below End If, add Wait and set it to 2 seconds. Without it the Home Screen can miss the update. Then add a second If: Shortcut Input, is not, lock.
5. Inside it, add Get Wallpaper for Now set to Home Screen, then Set Wallpaper Photo with Home Screen only, and turn off Crop to Subject and Legibility Blur.

Can't find Almanak's actions? Search for them in the action list after tapping Edit, not in the "Describe a shortcut" box. If they still don't show, restart your iPhone and open Almanak once.

Before the first run

Run on its own or from an automation, the shortcut changes both screens: the hour's picture on the Lock Screen and its softer partner on the Home Screen. Set Wallpaper Photo can only update a wallpaper that is a photo. Save today's pair from Almanak's Now tab, then in Settings, Wallpaper, Add New Wallpaper, Photos, pick it once. Almanak's shortcut updates it from then on.