I remember that nobody knew how Facebook would make money – after the IPO the price halved in fairly short order.
I saw that NextDoor came to the market as a SPAC – initially priced at 10 dollars – after the merger the stock had an initial run up to 12 and above. Then it sank and I was able to buy @7.49 on 21st December.
All I really know about NextDoor is that it focuses on verified members in areas, so you might find a plumber or electrician who is local and does not have to travel for miles. Also members can gift or sell unwanted items – useful now that care homes cannot accept a lot of stuff because of regulations, and local authority charges for removal can be quite steep.
Where there is street or driveway parking I have noticed people post reports and photos of people acting suspiciously, so it becomes a kind of neighbourhood watch.
So I will be interested to see how this company develops in 2022.