There's not a ton of information available on the breakdown of sales by platform, but the data that is out there shows Linux sales usually compromise ~2-4% for cross-platform games [1]. If you get linux support "for free" by utilizing an engine, then absolutely go for it, but even major companies with massively popular games are still skipping out on first-class Linux support [2], due to the low market share.
[1] https://www.gamingonlinux.com/articles/linux-game-sales-stat...
[2] https://www.gamingonlinux.com/articles/president-of-blizzard...