I am really jealous being an android user that Apple usually have this things running on their own devices with more privacy in mind. But I just can't accept the close garden Apple push.
They do say that they have privacy in mind. And they are also collecting the same data of their users as Google.
Don't be too jealous, they suck just as much as your next Android-Phone company. But with a higher price tag and a walled garden.
Funny that you mention it, a few months ago when updating stuff I got a new feature on my Android phone... Offline subtitle generation based on audio, just realtime generated from anything outputing sound on my phone.
A Google search suggests this might be an older feature - not sure if my phone didn't support it, or if I maybe just missed it, or if they added a more obvious button.
Google has a separate app for that stuff, called Private Compute Services. Right now it's nothing like an offline Google assistant replacement, but I thought it's really nice to have that stuff available without relying on internet access.