With RCS, iPhone users can converse with non-Apple users without losing the enhanced features to which they've become accustomed in iMessage. That includes longer messages, HD media, typing indicators, and much more. Google Fi has several different options for data plans, and the company notes that RCS does use mobile data when away from Wi-Fi. Those on the "Flexible" Fi plan pay for blocks of data as they go, and using RCS messaging could inadvertently increase their bill.
If that's not a concern, it's a snap for Fi users to enable RCS on the new iOS update. Head to Apps > Messages, and then find the Text Messaging section to toggle on RCS. It may, however, take a few minutes for your phone number to be registered with the Fi RCS server.
In hindsight, the way Apple implemented iMessage was clever. By intercepting messages being sent to other iPhone phone numbers, Apple was able to add enhanced features to its phones instantly. It had the possibly intended side effect of reinforcing the perception that Android phones were less capable. This turned Android users into dreaded green bubbles that limited chat features. Users complained, and Google ran ads calling on Apple to support RCS. That, along with some pointed questions from reporters prompted Apple to announce the change in late 2023. It took some time, but you almost don't have to worry about missing messaging features in 2025.