you can think what you want, but the apple website is very clear on this feature:
"On-device categorization organizes your messages and helps you stay up to date across all your accounts. The Primary category includes your most essential emails — like those from people you know and time-sensitive messages. And the rest of your email will be organized into new categories like Transactions for receipts and order confirmations, Promotions for marketing and sales messages, and Updates for newsletters and everything else."
=>
https://www.apple.com/ios/ios-18-preview/
It's not even listed as an apple intelligence feature but as an iOS 18 feature. This implies for me that it should work on every device including the ones who don't support apple intelligence