You want to buy a phone or a tablet and want to know if the app will be able to run on it ?
iOS devices will need iOS 11.0 or later
Android devices will need Android 8.0 or later. This has been announced by Positive Grid during the 184.108.40.20634 release on Nov 24, 2021.
Android 7.0 was supported prior to Spark app version 2.3.0
Related link : Does your iPad or iPhone supports version iOS 11.0 or later ?