My upcoming project calls for 1" crown staples to join 1/2" plywood pieces. What's a suitable alternative if I don't have a compressor/nailer?
Nails.
Reason I'm not specifying a size is it's up to you, since it's not just the size/gauge of a fastener that's important, but how many of them you use and how they're driven — with nails the correct way to maximise holding power is to drive them in 'dovetail fashion'. So if you for example use six nails along a joint then three would lean to the right, three to the left. This gives a direct mechanical hold beyond just the friction of the nails in the material.
Open to suggestions!
Ideally glue and nail.
Adding glue to a joint can add greatly to the strength once the glue has cured. Technically you won't need to use clamps if in addition to the glue you use nails or screws as the fasteners act like a clamp. It is generally very helpful if you can clamp the piece up for assembly though, but you can release the clamps immediately so that they're freed up for the next task if you'd prefer.
Note: very lightly sand both the end and the face of the plywood where the glue will be applied to freshen the surface, for this reason.