However, you should keep in mind that many lenders will either (1) not lend on the home if it has unpermitted living space; or (2) will require a comparable sale with similar unpermitted area (almost impossible to find).

For example, buying a single-family home in the middle of Manhattan is virtually impossible; you would probably be better off buying an apartment or townhouse.

It is impossible to predict the future and when the economy will slow down.

Running  comps is almost impossible for this building and in the area it is in, so determining an ARV is very difficult. 

Maybe they will stay until December but based on this I feel like most landlords are going to tighten their screening up which will make it hard if not impossible for people like this to find housing.  

It's next to impossible to address in an online forum properly.To illustrate my point, you could be talking about a highly appreciated piece of vacant land in a desirable area or a neglected commercial property in an urban area decimated by Covid or a cash-flowing beach property etc. 

Though it is more difficult to open an account as a foreign national I believe it is not impossible, but you do need to make a trip to the US as any bank requires you to be physically present with 2 forms of ID to open an account.Having lived in the US (went to college in FL) I'm lucky in that sense as I have bank accounts, a SSN and even had great credit although I'm pretty sure it's back to nothing after 14 years of absence. 

I am typically the "glass half full" kind of guy but It is nearly impossible to be completed and sold in that short period of time.

Not impossible - just hard. 

A typical newer 2-br condo outside of Vancouver is $600k+, and in Vancouver they are often $1M, so impossible to cash flow.