Great question! Your developer is right that matching the site name to the band name is important for branding. As for the domain, .UA is perfect if your main audience is in Ukraine — it helps build local trust and can improve local search results. But if you plan to perform internationally or reach a broader audience, .COM is a more universal and globally recognized option.
One idea: you could register both domains — use .UA for your Ukrainian audience and redirect it to
pgslot999 main .COM site. That way, you protect your brand and keep things flexible as your reach grows.