Membrane pores and transporters see millions of ions flow through them per second. This creates a current and therefore a magnetic field. Do cells have any use for these fields (like maybe drawing charged receptors together?) or is it physiologically irrelevant?
For currents in biological systems the magnetic field is minuscule, and likely has no physiological effect.
That said, magnetoencephalography is based on measuring the tiny magnetic fields created when nerves fire. Detection requires an incredibly sensitive detector, a superconducting quantum interference device (SQUID), to detect the location of the currents. A SQUID can detect fields of just a few atoteslas (aT)!
Perhaps one could investigate how much ion flow in electric eel muscle is constrained by the induced magnetic field... It could lead to shocking revelations.
A better answer starts by being more precise in the type of magnetic field (static for example) and magnitude of exposure.
I have conducted one small crude experiment employing a 'Magnetizer', which is encased in plastic, which is reputedly claimed to produce an ordered collection of strong and weak fields to leave a residual magnet footprint when a metal object is inserted (or fluid passes). The Magnetizer was placed in an open vessel with H2O (tap water with oxygen), Fe as iron filings, some dissolved CO2 from seltzer water, and a bit of sea salt (see https://www.sciencemadness.org/whisper/viewthread.php?tid=77204#pid493712 ). There was also another identical vessel with the same reagents, but absent the Magnetizer, as a control. The results, following periodic pictures, seemingly indicated a jump start in the Magnetizer assisted iron oxidation experiment. In fact, I roughly suggested that the presence of the ordered magnetic field as supplied by the Magnetizer appeared to increase the reaction rate by 20%!
Reading comments in the alluded thread experiment does reveal some of the possible complexities in setting up a rigorous experiment. I do believe that an alleged criticism relating to clustering of Fe particles (from the magnetic field effect) is in error, as I would argue, it is not an advantage to bury Fe particles thereby reducing contact with surface water rich in needed oxygen.
Also, the literature further claims that radical based reactions are also accelerated. In fact, I cited a reference in that study relating to the use of a magnetic field to reduce the amount of free available chlorine (supplied as tablets) normally added to a swimming pool in experiment conduct in England. That study also claimed measurable positive benefits.
So, there are studies (which may be of suspect quality also) asserting the effects of a magnetic field to be apparently very real and certainly not marginal.
To answer you question: Do cells have any use for these fields (like maybe drawing charged receptors together? My answer is perhaps.