Ulawa's airstrip in the Solomon Islands has no lounge, and none should be expected at a strip serving an island this size. RNA connects Ulawa to the rest of the Solomon Islands network on small domestic aircraft, and the honest picture is a single airstrip building with basic shelter rather than anything resembling an airline lounge.
The reason no lounge culture exists here comes down to the kind of flying this route actually is. Solomon Islands domestic services to outer islands like Ulawa typically run on small turboprop aircraft with limited seating and no premium cabin, so there is no first or business class to build a lounge product around, and no elite-status tier locally that would justify one. This is a genuine inter-island public transport link, not a premium travel product, and travelers should plan their expectations accordingly rather than hoping for an overlooked facility.
Honiara, the Solomon Islands' capital and home to Honiara International Airport (HIR), is the country's real aviation hub and the place where any premium airport experience in this part of the Pacific would actually exist. Passengers connecting through Honiara on their way to or from Ulawa should look there for anything resembling a lounge, and even then, expectations should stay modest, since Solomon Airlines' network is built primarily around point-to-point domestic and limited international service rather than the extensive premium infrastructure of a major regional hub.
If your itinerary includes Ulawa, the practical approach is simple: treat the airstrip itself as a basic waypoint, bring your own snacks and water for what can be a wait in open-air or simply covered seating, and save any lounge expectations for your connection through Honiara or wherever your international journey actually begins. Confirm current facilities directly with Solomon Airlines before you travel, since small island airstrips can see infrastructure change with little notice.