4GB of system RAM won’t leave much use for Nomad for intense work - the Air 4 has 4GB, and Nomad can utilise 2.7 of it. Take into account the older processors in the older iPads, they’re good for iPad-centred tasks and 2D work, but pushing it into the realms of 3D - especially when you begin adding lights, turning on heavy post processing, high textures, etc - and using features like dyntopo will clunk it down. Considering Apple are refreshing their iPad line up this year, the new Air 5 is set to be announced during their Spring Event (April/June time) - with a refresh to their pro line up supposedly toward the 3/4th quarter of the year. For future proofing, it might be better to wait and pick up last years line up when they become the ‘older’ generation this year - and thus, cheaper. (Apple move quick).