Ok, let's go over that.
Not enough population
ENSB is the northernmost civilian airport in the world. The town has a population of 2368 which is not a lot but it's unique location makes it special. It draws a number of tourists as well as scientists for the world seed bank which is located here. Together with tourist and business/science charms it could very well work in the game.
PAOM has a population of 3870, which is more than Longyearbyen. For a remote Alaskan town this is a lot. Besides, it has a unique position in western Alaska and could be used to bridge Asia and North America on a regional flight for airlines with insufficient population. Potential transfer traffic here.
PABE has a population of 6585 making it one of the larger remote towns in Alaska. Furthermore, the same thing goes as for Nome that it can function as a bridge between Asia and North America. Besides, these small Alaskan airports are great for bush flying.
YLHI is a remote island between Australia and New Zealand. It has a population of 382 which is very little, but does see some tourism. In fact they even had to cap the number of tourists on the island to 400 at any time to prevent it from being overrun by tourists. With tourist charm it can definitely work in the game.
Without scheduled service?
ESKS does have scheduled service on SAS, although seasonal. Also several airlines fly charters to this airport. It was constructed to provide access to the skiing resorts in the mountains, every winter a good number of people go there for a holiday. That means tourist charm.
FHAW doesn't have scheduled service, but does see frequent charter flights on Airlink which connect this remote island to the rest of the world.
HEMM does have seasonal scheduled service on Neos to several Italian airports.
HETB doesn't have scheduled service, but does see frequent charter flights on several airlines.
HTDO does have scheduled service on several airlines.
KGYY does have scheduled cargo service. It's also able to handle passenger flights, but no passenger airlines fly there at the moment.
KIAG does have scheduled service on Allegiant to several destinations. It also handles some scheduled cargo flights.
KIWA does have scheduled service on several airlines including Allegiant, which has a base here.
KJQF does have scheduled service on Allegiant to several destinations.
KPAE does have scheduled service on several airlines including Alaska Airlines. It also handles some scheduled cargo flights.
LDOS does have scheduled service on several airlines such as Trade Air.
LELN does have scheduled service on Iberia Regional.
LFOK does have scheduled service on Ryanair, plus some scheduled cargo flights.
LFRG does have seasonal scheduled service on several airlines.
LICB does have scheduled service on several airlines including Ryanair.
LRCV does have scheduled service on several airlines including Wizzair.
OAKN does have scheduled service on several airlines, both passengers and cargo.
OIHH does have scheduled service on several airlines including Iran Air.
PAEN does have scheduled service on Grant Aviation.
PAHO does have scheduled service on Smokey Bay Air.
PASC does have scheduled service on Alaska Airlines.
PWAK doesn't have any scheduled service, but it does see frequent charters on Air Transport International.
SCRM doesn't have any scheduled service, but does see frequent charters on Aerovias DAP. It's the only commercial airport in Antarctica and despite it's small population coverage (only 150 people live there permanently) it does attract tourists and scientists so with according charms it can definitely work in the game. Besides, it's just cool to say your airline serves every continent including Antarctica.
VIAG does have scheduled service on several airlines. Deserves tourist charm due to the Taj Mahal which is located here.
VIDX does have scheduled service on several airlines. It was built as a reliever airport for Delhi.
VIJR does have scheduled service on several airlines including SpiceJet.
VOPC does have scheduled service on SpiceJet.
ZGWZ does have scheduled service on several airlines including Shanghai Airlines.
Indeed, a number of airports are entirely without scheduled service. But by far not all of them.