Alberta could collect its own provincial income tax instead of leaving it to the CRA, the way Quebec does.

This is something a province can already do inside Canada. Quebec is the only province that runs its own personal income tax system through Revenu Quebec; the Canada Revenue Agency collects personal income tax for every other province under tax collection agreements a province is free to leave. Alberta already administers its own corporate income tax rather than using the CRA, so extending that to personal income tax would be a question of cost and administration, not constitutional power. A Quebec government review found running a separate system is more expensive, which is the main argument against doing it.