Are you aware of the option called "read list" on browsers? For Chrome, you can just go to your settings and add the exact thread you want to save in your read list, which you can easily go back to anytime you want, and it will just be accessible.

It's more organised than just bookmarking. Another suggestion which I can also give to you is keeping such a thread open in a different tab and never closing it; anytime you want to go back to the thread, you can easily check your inactive tabs and locate it there easily. Both options are available for mobile and desktop users.