Mastodawn

Download Firefox from Safari. Set Firefox preferences…

Set as default browser.

Add English (GB).

Install Translations add on.

Turn off "Sponsored shortcuts".

Do not save passwords (use a dedicated password manager).

Set Duck Duck Go as default search engine; remove ebay.

Set Strict privacy, tell websites not to sell or share my data, send websites a "Do Not Track" request.

Add Multi-Account Containers, add some containers.

Delete cookies on restart, add some allowed sites that live in their own containers and stay logged in.

Right-click bookmarks bar on new tab and set to Never show.