I think you are making a mountain out of a mole hill here my man. Having no questions asked 14 days to see if you like not only the form factor but also the stock OS sounds pretty good. I think it’d be just as annoying to hold the phone for 5 minutes, buy it, and then find out later you have gripes with the OS that you don’t like.
Even though you think it’s annoying to do, it might be worth the trouble to atleast try the phone you aren’t familiar with.
I mistyped my bank website at an insurance office and locked down the computer. Lady had to call IT to unlock everything again. 16 year old me learned to carefully check the address bar that day.
I think you hit the nail on the head with diminishing returns. I’m usually on a 5-6 year usage period too. I can understand the battery swap helping out but my last few phones have felt so sluggish after 4+ years so I start looking at new phones around year 5. I have a Pixel 7 now and I’m going to wait until end of support and then we’ll see what the offerings are then!
You could try Niagara Launcher. I’m using it and it’s got that decluttered home screen but it’s fairly minimal. It’s worth mentioning you do get most relevant features in the free version.