Keyboard arrow keys

In case anyone checks this who knows what to do: the linked site doesn’t seem to exist anymore. Would someone please be so kind to write or link to detailed explanations on how to achieve remapping to any “superfluous” key that’s closer to the arrow keys, so they can be used in their alternative state, as page up/down/pos1/end? For Linux and Windows? It’s really annoying being told no-one uses those alt functions a lot, when people actually just maybe have decided not to buy a Framework laptop even due to the size of those keys.