Devolution is about devolving power. There’s a clue in the name.
Which is why talk of English devolution that slips into talking about English MPs voting on English laws misses what English devolution should really be about. Not about a smaller number of MPs keeping power still to themselves, but about devolving power away from MPs downwards to local government (and possibly regional government, though the appetite for creating a new layer of government across England is fairly limited – better to look to soup up existing local levels rather than create new ones).
Meaningful English devolution isn’t about which MPs get to vote on what in Westminster. It’s about what councillors, Mayors and London Assembly members get to decide in future that MPs currently control.