Your very dated S4 mini was a bit of an outlier even back in it was released back in 2013. Unfortunately, the trend the manufacturers have taken is to make bigger phones, despite a sizable number of people like your wife who would prefer a more easily manageable, smaller phone. I'd recommend you avoid getting any phone that's also dated simply because its smaller, the problem being unsupported phones are more likely to have more security and privacy weak points. Things are bad enough with new and newer phones now, intentionally buying an older phone that's already outdated involves increased risk.
Another phone that matches the 4" size of your S4 mini is going to be a challenge. Newer Android phones tend to be in the 6" or more category, with a few older models still in the 5" plus range (the 2020 Pixel 4a is a very solid performer and with a 5.8" screen) but look at something like an Apple iPhone SE (2020 - 4.7") if that size factor is a must.