This would be pretty easy to achieve, you’d just need a card or big button upgrade like “Neo-Incan Reforms” to reform their unit roster and give them Bolas Riders and Light Cannons. Unlike the Aztecs, the Inca actually survived long enough to adopt European technology like gunpowder and horses.
Bolas Riders should just completely replace Bolas Warriors after the upgrade. It would also be a blessing for playing against Inca since you wouldn’t have to struggle to distinguish between the extremely similar looking Bolas Warriors and Huaracas. Bolas Riders should just be a standard unit instead of a native one and could be shared with a future Mapuche civ.
Light Cannons getting trained from the Stronghold would give them reasonable anti-artillery and let Huaracas be toned down into a more reasonable Abus/Grenadier unit.
There are also Macemen and Chincha Rafts that are supposed to fill way more roles than they should be doing.
Chincha Rafts do the heavy lifting of an entire navy so adding some smaller Balsa Boats as a canoe equivalent would take some pressure off and make Chincha Rafts a less gimmicky unit.
Inca should be given Rams so that Macemen could take on a role other than siege unit. Rams would first need to not suck so some changes like this could be done:
They’re also chocked full of other BS like military garrisoning, converting priestesses, factory houses, invisible forts, and way too speedy pikemen that I think could be scrapped or reworked.