I like @miroxlav's Autohotkey answer but it doesn't work without modification on my own keyboard. Rather than muddy his answer any further, I want to clarify my own usage case and what my solution is for that usage case.
Like the OP, my keyboard has < and > symbols on the comma and period keys next to the "m" key on the bottom row, near the right Shift. I live in the United States and we do not have keyboards here with an AltGr key. Instead we have two Alt keys; one on each side of the space bar. So my keyboard is like the one the OP is asking about.
I am on Windows 10 and have installed a Spanish keyboard layout as a secondary layout so that I can easily write accent marks and tildes for Spanish writing. The problem is, there are no < or > symbols included in that layout.
What I have found from a little bit of research and experimentation is that this layout replaces what is sent by the physical right Alt key--instead of sending right Alt it sends an "AltGr" keypress. In that way, I can press the physical right Alt key plus the "q" key and get "@" as a result. This is as intended, as there is no other way to get a "@" when using this Spanish layout.
But, there is no way to use the right Alt key to get < or > symbols.
So, here is where an Autohotkey script comes in. However, Autohotkey does not seem to recognize the right Alt key as sending an AltGr keypress, even though Windows 10 does, and the right Alt key no longer sends right Alt keypresses when using this layout either.
So, the problem is: Autohotkey does not recognize the right Alt key as being pressed if we use a script that says the right Alt key is pressed nor when we say AltGr is pressed. Neither of these is recognized:
>! ; right Alt
<!> ; AltGr
What I've discovered is that Ctrl + Alt is another way to send an AltGr keypress. And, Autohotkey recognizes that Ctrl + Alt are pressed when the physical right Alt key is pressed! So, this will be recognized:
^! ; Ctrl + Alt
However, I don't know why, but Autohotkey does not like it when I put the entire shortcut on one line. So here is the script that works on my machine. This script will send < and > symbols when the physical right Alt key and the comma and period keys are pressed, respectively:
; AltGr + , sends <
; AltGr + . sends >