More powerful kit produces more work, but every scientific result is valuable; I run BOINC on a modern PC, an old Laptop, 2x Raspberry Pi and 3x Android phones. iPhone / iPad are locked down and can't work with BOINC.
Gridcoin can't run on Android for mining but apart from that it's also very flexible.
Pretty much any computer you have can work for Gridcoin, of course servers and gaming PC will earn more than an old Laptop, but the science you do will be of great value.
I actually have it running while I'm at work on my laptop. Not a lot of power at all, but I have the 8 hours to put the computer to work.