I'm not that great with this genre as I immediately start thinking "Steam Punk". However, given that you mention indie authors, I thought I would do a bit of a search for you.
Dawn Crescent - David Dvorkin ("Engaging characters and fast-paced writing make Dawn Crescent a real pleasure!" - Harry Turtledove.)
In 1991, at the beginning of Desert Storm, the defeat of American forces at the battle of Khafji is the signal for a broad and bloodily successful anti-Western uprising. In this alternate history, America faces endless war in the Middle East, a resurgent Soviet Union, and growing tyranny at home.
Budspy - David Dvorkin ("Smart, fast, and mean" - Kirkus. "Involving." - Booklist. "Masterful." - Asimov's. "A well-told tale of crime and conscience." - Indianapolis News)
Decades after defeating the Allies in World War Two, Nazi Germany rules Europe and dominates the world. But there’s rot at the core of the Reich, and an American agent is assigned to help the Germans root it out.
Beneath Gray Skies - Hugh Ashton
Beneath Gray Skies describes a 1920s world that might have been, had the American Civil War never been fought. The new Nazi party in Germany, Confederates, and British and American intelligence services engage in intrigue and treachery, as the giant Bismarck–the largest Zeppelin yet constructed–crosses the Atlantic carrying a priceless gift from the Old World to the New.
I can't really vouch for any of these I'm afraid, but I thought seeing as you specifically mentioned independent authors as a preference I'd try to throw a couple into the mix. I think David Dvorkin might be worth a look if Harry Turtledove himself has given (or sold
) his endorsement.
Regards
Caleb