Difficulty remapping AltGr to regular Alt key on brazilian ABNT2 keyboard

Question

I have a Brazilian ABNT2-laidout keyboard and I really need to remap my AltGr key to function as a regular right Alt. So far I've tried:

• Using the SharpKeys application;
• Enabling and disabling AutoHotKey;
• Installing the ABNT1 layout to Brazilian Portuguese to use instead of ABNT2.
• Using Keymapper (this one didn't even run; was it a bait to get me infected?) https://github.com/stuartd/keymapper/blob/develop/KeyMapper.exe
• Following this Q&A here on SU.

Nothing worked.

I almost inserted some registry tweak I found around, but I got afraid I wouldn't be able to revert it.

The only thing that worked was installing the English-US layout, which is not acceptable; only then the AltGr key behaved just as Alt.

Using AutoHotKey is not an option because I already use it for something else that would conflict.

Any clues?