Hi King Steuie - welcome to the forum!
My advice with 1/64 scale HO track is almost always to stick to one system. As Andy P said, a DIY adapter might be okay 'for fun', but is likely to be very disappointing for longer-term use. There are adapters available for some American brands - AFX to Tyco, AFX to Life Like etc - although these can be tricky to find and expensive. There is the one adapter for Micro Scalextric - to the old Marchon / Scalextric Micro MR-1 track system.
Can you give us the names on the boxes of all three of the sets you have. That will help me with figuring out what you have and whether it is compatible.
Am I right in thinking your Giant Raceway is the Tomy AFX set? The lane spacing on AFX track is narrower (by a few millimetres) to the 1995-2019 Micro Scalextric track. That does make an adapter tricky to make. There is no commercially-available adapter from AFX to Micro.