You're on the right track to reach out for help here and also to look to your area for potential partnerships.

Now, I have not tried this but in practice I see no reason why I could not use a service (Plastiq, Venmo?) 

Not only can you collect rent to go towards your mortgage, you're also building equity that can potentially be used down the road for your next home or investment.

Conducting a thorough property inspection or consulting a contractor can help identify potential large-ticket items you might need to replace soon.For make-ready costs, you can look at local averages for common turnover tasks like repainting, carpet cleaning, or minor repairs.

.$100k can potentially be deducted as replacement debt. 

Instead of jumping into an expensive Long Island market with negative cash flow, consider investing in a Texas market like San Antonio, Houston, or DFW suburbs—these areas offer strong rental demand, lower property taxes than NY, and better cash flow potential.

We fully renovated both units, improving the property’s value and rental potential.

Find a good lender, get pre approved, make sure you practice running the #'s using the 100's of videos and guides from BP, find an investor friendly Realtor, and then start making offers on any property that meets your goal.

It is cheaper then FHA mortgage insurance, and you can potentially drop it in the future without refinancing unlike FHA. 

So someone who is looking purely to maximize potential return (and has unlimited time) is unlikely to find this a good fit.