Over the years, I’ve learned that I don’t need to physically be at a piano to be able to practice. I mean, I prefer practice at a piano, but there are some times when that’s just not possible.
Listening is always an excellent way to practice. You can sit and concentrate on the phrasing and emotion of the piece.
Visualizing a piece as well is always helpful if you have it memorized, even small sections you might have been working on.
Another way that I practice, is to just practice the fingering of a piece on a table, carpet, etc., preferably on a surface quiet enough not to annoy people. I did this when working the right-hand on a Chopin piece years ago while watching a movie, and surprisingly, it was applied successfully when I got back to the piano.
I can’t guarantee that will work for everyone, but for myself, it cemented some patterns I’d been working on for awhile.
Off to find my piano.