It’s been a long time but I’m sure we were able to mulch our leaves with the push mower once the blades had been properly sharpened. (Where I live now there’s an unfortunate deficit of leaves (you could always try posting some of your excess to Scotland ;) and in between I was four floors up without a garden). A bit large if you don’t otherwise need a mower though but going for a walk across the grass is some of the easier garden work.

I’ve seen videos of people making contraptions involving things like rotary saw blades and hand cranks but that’s way far beyond me. I do like watching clever gardening videos though, especially in January when it feels like winter will never end.

Good luck finding a solution.