onTrak by Agricision vs Agribus-navi (with quartz 818xt)

I bought a quartz 818xt receiver last year, and used it with the agribus-navi app on my android phone. Had reasonable success though the app crashed a couple of times and on restarting the gps wasn't entirely accurate (eg. gps was off when going back through a gate I have been through previously).

Since then my android phone died and now have an iphone (the iphone was not far off the price of the google pixel phones).

Question is do I buy a new android tablet - circa £80-100 and continue...

onTrak by Agricision vs Agribus-navi (with quartz 818xt)