Possible, but potentially not as practical due to the iOS’ restrictive background process model. There, background tasks are generally expected to quickly do whatever it is they need to and exit and generally can’t run indefinitely. Periodic tasks are scheduled by the OS, with scheduling requests from apps being more likely to be honored if their processes are well-behaved (quick, low resource, don’t crash, and don’t run too frequently) with badly-behaved processes getting run less often.

Apps that keep themselves open by reporting that they’re playing audio might be able to work around this, but it’d still be spotty since users frequently play media which would suspended those backgrounded apps and eventually bump them out of memory.