Interesting Jeffrey, a big difference is Germany had multi parties, we have two major ones and a bunch of third parties that don't count. Also the NAZI's didn't write Germany's election laws as Republicans and Democrats do here, today. Germany at that time was under a proportionality parliamentary system, not a two party system.
Lots of differences. Today, Democrats and Republicans expect independents to bend to their will. Neither really tries to attract independents although, independents do decide national elections, 2024 in your case.
Also you're ignoring the fact a majority of independents don't like Trump as proven in the 2018 midterms, 54-42 for Democratic congressional candidates and the 2020 presidential, 54-41 for Biden over Trump.
2022 is up for grabs, at least the House in my estimation. The Democrats should pick up 1-3 seats in the senate unless something very unforeseen happens that goes against the democrats. I also don't think either party can unite with independents or that they can't do much to attract them as a group as they're way too diverse. Trump has managed to drive the majority of independents into the Democrats column. That's where they stand today, tomorrow is unknown. But as long as Trump keeps being the face and the leader of the GOP, that coalition, fragile as it is, will probably hold.
2024 will depend on the two candidates. Please, no more Hillary's which a vast majority of independent didn't like. Biden was likable, Hillary wasn't and neither is Trump. Now 2022, I think at the moment the senate is safe. Until redistricting takes place, the house is an unknown factor. Probably much depends on whether the Democratic controlled congress does something or passes something that make independents angry at them. I would add if Trump fades away, that would dim the the democratic prospects of keeping the house.
I think the best way to keep independents happy is not to over do it. Certainly not to pass something a majority of Americans are against; Bill Clinton in 1994 and Obama in 2010 made that mistake. It resulted in a 54 and 63 seat loss. I'd also say lose the stupid slogans. Greger doesn't agree with me, but I think and the polls show Defund the Police slogan was the main reason the democrats lost 13 house seats, 2 state legislatures and a governorship in 2020.