An action/activity log is just a reverse-chonological log of things that happened. You could make one by recording every would-be toast and putting it on that list, complete with a timestamp, and any of the context-relevant action buttons (like "undo", or "view item", etc.). The list should be a fixed recording[0], without any way to dismiss some or all of the entries. Add some attention-grabbing indicator whenever something is added there, and you get all the benefits of toasts with none of the drawbacks: the log lets you report completion of optimistically-executed actions, provide place for context-relevant buttons, and also is accessible, can be browsed at uses' own time, improves discoverability and learning, and can be upgraded to also enable undo feature.

--

[0] - Well, appended from top, and possibly unwinded by undo. Users understand that. Can't be append-only, because mixing that with undo gives you the undo system from Emacs - very powerful but also nearly incomprehensible to most people.

https://en.wikipedia.org/wiki/Pop-up_notification#JavaScript