Without naming names, there's a well advertised grammar editing tool that's available either as an app download or browser extension. This is something I'd value for a number of reasons (good grammar is important!) but I'm super cautious about anything I'm giving permission to watch what I'm typing.

Ideally, I'd prefer to select text and have it analyzed on-demand using on-device intelligence. I'm on a Mac and it seems like Pages isn't cut out to check grammar. Also, there's no way in heck I'm paying $30 a month for a subscription.

Edit: I just want to acknowledge my request for something I'd value and then saying I don't want to pay for it. I would certainly pay for something if it met my needs but this function isn't something I'd personally value at $30 a month or any monthly subscription ($30 a year sounds reasonable). Moreover, if there's any suspicion of an application using my data for their own profit, they are not getting my money. So, in this case, for the sake of data privacy, I would prefer to pay for something (preferably once - grammar shouldn't need updating).