I have 3 mid term 3 bed 2 baths SFL homes in charlotte.

Weekly conferences with the buyer etc so they monitor progress. 

Be sure you can attract health care travelers at the price you would need to make it net more than long term. 

They fall under long-term rentals.

There are options  to use ADT sensors etc on a self monitored system but it can get complex and you are better of moving to a more turnkey system. 

They were major BRRRR projects with the main exit strategy being to hold as medium term rentals.

They should understand you want to keep them long term but you are running a business not a charity. 

I just purchased a property and would like to replace the locks and thermostats to something I can control through an app and give codes to the renters. Any suggestions? Google Nest is being discontinued, so not sure ...

Why would you want medium term? 

Quote from @Ashish Acharya: @John Underwood For tax lien properties, the start date for determining short-term vs. long-term capital gains begins when you legally acquire the property, not when the lien is initially purchased.Key Tax Insight:Holding Period Start: Under IRS rules, your holding period begins when you receive actual ownership (title) of the property, not when you buy the lien.