I've seen several Q&As on recycling and reusing plastic from failed prints, but what have you done with the last few meters of filament? I've been keeping the ends of PLA (or sections I needed to cut) to maybe use for friction welding pieces together, but I only need so much for that. I've considered just shoving the last bit in the tube and using a new roll to push it through (so long as retractions aren't necessary).
This is especially a concern for more exotic filaments where friction welding isn't useful and the price is higher for that 1m section (something like Copperfill).
Note: I have a Bowden extruder. I imagine this is less of an issue with DD extruders.
Weld the fragment to the beginning of a new spool and use it that way. Most are made from metal so they aren't that easy to make at home. Here is another answer that lists other methods to weld filament including using heat shrink tubing.
As you mentioned, you can use it for friction welding.
Use it for pin/studs/rivets/hinges in prints.
Throw it away. 1.75mm * 1Kg is about 330m of filament, 3mm * 1Kg is about 110m of filament. The leftover isn't worth much when you consider how much is on a spool.