device-agnostic
adj. Of, or relating to, a software program or other system that is not dedicated to a single hardware platform, but instead is flexible enough to work with any device.
Examples
2000
uMonitor can be done on the PC, palm pilot, two-way pager or wireless simultaneously.

'We are device agnostic and account agnostic,' Bolen says.
—“uMonitor.com to unveil wireless software at bankers conference,” Memphis Business Journal, September 08, 2000
2000
What we really provide is a device-agnostic, protocol-agnostic and carrier-agnostic access to any wireless device.
—Antony Bruno, “Datalink.net shifts focus to business market,” RCR Radio Communications Report, January 31, 2000
1996 (earliest)
The most likely solution for any large-scale program, however, is a device-agnostic approach, allowing for a flexibility among user interfaces that could meet the demands of the broadest possible audience.
—Thomas Maresca, “Electric Companies to Jolt Industry,” Interactive Home, February 01, 1996