For years I had a sheet of little red arrows (on clear plastic stickers).
I used them up, I can't find where to buy more. I used them to put on pressure gauges at startup to show plant personel where the needle "SHOULD" point to.
If you don't get a lead to replacements, maybe there's a make-your-own substitute?
We use the Brother P-Touch brand adhesive label tape printer machines, that make the labels that can be 1/4", 3/8", 1/2" high, with custom printing produced by typing on the QWERTY keyboard on the machine. The labels are adhesive on the back and stick to glass really well.
The tape cartridges are sold as, "color print on color background", for example, "black on white".
You would need "red on clear" to get a red arrow on a transparent label.
On the printer on my desk, I made a simulated fake arrow with characters under the symbol key. The printed version looks better than the ASCII text below, because there's actually an arrow head in the symbol set, not just an angle bracket.
There's a zillion bropther label printer models so it really depends on whether the red on clear cartridge is available for any particular model, and whether the symbol set works for you.