Most modern gadgets have switched mode power supplies, these should be
fine with modified sine waves.

Some equipment has linear (aka regulated) power supplies, these may not
like modified sine waves.

Generally linears have big transformers (and big capacitors) in them,
switchers smaller ones or none at all. But that isn't a guarantee.

The problem is the dc component in modified sine which causes an
excessive heating effect in linears.

You could try plugging it in and see whether it runs alarmingly hot.