It's probably a bit challenging to create any sort of non-contrived "early modern-themed" science fiction setting that doesn't feel at least a bit 1950s-ish because there are crucial elements of modern mass society that don't really exist before that period. For example, how do you do a late 19th century-themed television advertisement? It doesn't make sense for BioShock Infinite-style 30 second kinetoscope animations to still be in use in the actual far future.
While some of this is true, this shouldn't be oversold. 19th century & early 20th century periodicals have
fantastic and hilarious ads that you could use. And folks in that period were already worried, exasperated, and amused by the over-the-top, baseless, ubiquitous nature of advertising. Here's a c1899 French illustration that satirically predicted what advertising might be like in the future:
Victorian sale of chemical 'medicine', which often ranted about Far Eastern mystics endorsing their mercury mix or something, is easily evocative of even modern day morons buying vampiric mist sprays off goop. Here's a relatively harmless one about Cocaine for kids, and actually an American one:
And I've already posted Mucha, who came to dominate our memories of what fin-de-siecle Paris physically looked like all over the streets, not just in the pages.
More generally, Look at Cote's postcards that
AwesomeButton posted. I have copies of these in my bookshelf, as Asimov published them in a small book called
Futuredays. Look at, say, the postcard on educating kids through some kind of electric magnetism. It bears all the imprints of the later 19th century fascination with electricity as a possible medium for telepathy, but you can also see it could easily feature in a mid-century cybernetic fantasy about information processing.
So of course there are many echoes and continuities between 1890s and 1950s America, especially in terms of technological fantasies, corporate power-building, and the burgeoning consumer society. So no matter what they did, this was always going to be evocative of Fallout. But what they
didn't need to do was have half of your trailer look like it could be in a Fallout mod, have your run & gun gameplay
entirely copied from Bethesda games and nuFallouts, and have your environmental assets look more or less like a bombastic version of Fallout with some horrible colour vomit thrown in.