It is possible it would work but it is not tuned for GMRS. Antennas that are not tuned for the frequencies you transmit on present a higher SWR to the radio. The higher the SWR, the stronger the signal reflected back from the antenna to the radio. Some folks have reported for example that Midland GMRS radios can only handle a max SWR of 1.5:1 and anything more than that warranty is void. If that is true and you put an antenna on that exceeds that value you are living on borrowed time. Some radios can handle SWR upwards of 3:1. (Some high power expensive amateur rigs have built in automatic antenna tuners). High SWR support is great on one hand as it means the radio will survive and your investment is reasonably protected from a poorly tuned antenna. On the other hand, an unnecessarily high SWR number means you are wasting extra power in your cable, thus reducing your range.
If you had a quality SWR meter and you have confirmed it was within a safe range for your radio, buy all means use it. If you do so without verifying, by all means put your radio in lowest power mode to prevent letting the magic smoke out.
BTW, about a month ago I checked my personal Comet Dual Band Amateur antenna with an antenna analyzer for the exact same reason as you. While I do not recall the exact number, I concluded it was too high risk for my radio. So I carry two antenna in my car. I swap them as needed to suit the service I want to use.
Regarding antenna recommendation. I shared that I personaly use the Midland MXTA-26A. I have no complaints with it. I would buy it again.
That antenna is a dual band amateur radio antenna. While it may work, it is not designed/optimized for GMRS frequencies. I would expect the SWR to be high, perhaps higher than your radio will safely tolerate. I personally would not use it without first verifying SWR is appropriate and modifying it to suite for GMRS.
Modifying a dual band antenna is not for the faint of heart.
Purchasing one designed for GMRS frequencies is what I recommend. I personally use the Midland MXTA-26A GMRS antenna and have zero complaints.
