Is she willing to buy a new phone and wipe it with LineageOS of GrapheneOS? If not, start off with FOSS alternatives to apps she already uses. Going with a full system replacement might be a make or break situation, depending on if she relies on NFC payment, or a certain banking app that doesn’t work.

If you can convince her to:

• Use Signal for messaging friends (and if she can convince her friends to do the same)
• Purchase a domain so she’s not locked down on her email address when changing email providers (I recommend Tuta)
• Avoid algorithmic control by only following subscriptions with the help of frontends like Newpipe for Youtube
• Avoid Spotify by 🏴‍☠️ or purchasing the music from Bandcamp
• Browse Droidify for any generic app she wants (music player, notes app, etc.)

This should help settle her in more. She could buy a used Pixel 8 and install GrapheneOS. Motorola also plans on releasing a GrapheneOS phone, so could be something to look forward to.