FOSS apps are generally more secure due to auditability of the source. Many eyes, and all that. Although I’m sure there’s also reduced interest from attackers on smaller platforms.
Also, malware devs would have the additional constraint of having to either open source their malware, which they probably don’t want to do, or sideload their payload, which is more work for them.
Yeah, the high end 9 series are (were) great. I’m still using my S9+ and just don’t have any good reason to “upgrade”. I don’t intend to get a phone that doesn’t have a headphone jack and memory card slot.
I do kinda miss having a stylus, though, having come from the Note 4 previously.