I got 2 jackfruit seeds the summer before last, at a farmer's market when the guy was giving out samples of the fruit. I wrapped them in wet paper towel and put them in the fridge in a ziplock and forgot about them for 2 weeks lol. I planted them in miracle grow in pots outside and they both sprouted. So yes they can stay viable in the fridge for awhile. Probably not the freezer though.
Right now, I have a bunch of rambutan fruit in the fridge. Hopefully they will be okay to plant the seeds lol.