This is easy as I’ve been nerding out on privacy for more than a decade at this point, but privacy.com is the move here! It’s a phenomenal service (even their free tier) which lets you make one time use cards, cards locked to a specific business, or just general use cards. You can set spending limits on all of their cards, and you can set these limits for a defined period of time. Privacy.com is the bee’s knee’s, truly don’t know what I’d do without em these days!

LibreOffice works with LanguageTool, which is basically just open source Grammarly. So maybe give that a go and see how it works for you.