You should really try Elephas if you haven't already. GPT-3 swiss army knife for macOS (and iOS in beta) --> works anywhere you can type.

affiliate link: https://gumroad.com/a/633306323/ntmtp https://i.imgur.com/E3tGJAU.png

1. Take all things as seriously as you take yourself.
2. Don't take yourself too seriously.

Would consider as a one off lifetime alternative to Grammarly?

Hmmm, not quite. I don't think the grammar correction as quite as robust and legible as Grammarly. e.g., doesn't underline the issues.