The short answer on Linga Linga Airport (LGN) and lounges is no; the longer answer is really about how Papua New Guinea's whole aviation system works. PNG's terrain is famously mountainous and roadless across much of the country, so a dense network of small regional airstrips like Linga Linga exists to move people, mail, and cargo where roads simply cannot reach at all.
That airline-service picture explains the missing lounge better than the strip's size does. Rather than scheduled jet routes with passenger amenities, strips like Linga Linga are served by small aircraft operated by regional carriers and mission aviation groups built specifically around PNG's rugged geography, prioritizing utility and reliability over anything resembling a business-class experience. A lounge depends on a certain volume and category of ticketed passenger flow to justify its existence, and that pattern simply does not exist at strips built for light-aircraft utility service like this one.
For genuine airline and lounge infrastructure connected to a PNG itinerary, Port Moresby is where the real options begin. Jacksons International Airport (POM), the country's main gateway, carries the kind of airline lounge and premium-fare access that a small regional strip like Linga Linga was never built to offer, serving the long-haul and connecting international traffic that passes through the capital daily. Travellers with business in the areas Linga Linga serves typically connect through Port Moresby rather than expecting lounge amenities at the smaller strip itself.
Schedules on small PNG airstrips like Linga Linga move with aircraft availability and route economics more than with a fixed timetable, so a call to the operator ahead of your trip is worth more than any listing you find online. Whatever the current flight situation, route any lounge expectations through Port Moresby's Jacksons International instead, and treat Linga Linga as working infrastructure for the region it connects rather than a stop built around a pre-flight wait or a lounge visit.