As Firefox is by far my most used app, I find that bookmarking the current tab and describing the task with no more than a few words or even as little as a few chars, to be a good way to keep track of what things I need to do soon. For things I would get to later or whenever I feel like it, I’ll put them in Firefox’s “Boookmarks Menu” or “Other Bookmarks” folders, and have lots of folders consisting of Reddit posts and searches about different topics.
Normally, I would respond that I don’t do that, because I keep forgetting about those bookmarks, but now you’ve reminded me that I did pin something there last week …and then promptly forgot about it. 🙃
If you like playing with Bookmarks then i strongly recommend Tab Stash extension, I used to use it from the side bar, but when I discovered it can be opened as a tab, it’s has become the first tab I open in every session
So to answer your question, yes I do use Bookmarks as a To do Tomorrow, To view later, To Researcher in the future… Etc
I’ve been doing so for decades. I also use it to save recipes, which is a terrible idea because they tend to disappear eventually.
I use a kanban board that I made in HTML and CSS as a to-do list when I need one. I should host it somewhere and bookmark but eh, it works as is.