If I threw the money into SPY, it would be a 104% gain compared to walking away with an 80% gain after fees/commissions.

To decide, consider your ultimate goal, manage more tenants, and analyze potential fourplex properties to compare their returns.

What are your thoughts on its potential to deliver financial freedom quickly compared to traditional real estate investments?

Rents are up  compared to 2020 in my area.

If you compare ADU addition with any larger development effort , either in size of unit or number of units, the return is greater because building single small unit is the most expensive residential development.  

Basically when you compare Cleveland to Riverside, California most every Cleveland deal will look amazing to you on paper.

When you are comparing a condo to a SFH there aren't many pros but there are a lot of cons.

For Livermore, the activity is slower compared to the general Bay Area so you would need to be more cautious on picking the right property to flip, and the margin has to be large enough for it to make sense.

Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.

How do the interest rates usually compare between the two?