A64 (the SoC for PinePhone) is mostly intended for set-top boxes (i.e. smart TV), so it is really not designed for power efficiency.
It’s really a bummer that most “smartphone” SoCs cannot easily be purchased, and have no proper documentations. Thinkers and smaller manufacturers are stuck with mostly Allwinner and Rockchip SoCs (most of which are engineered as embedded processors) if they want to design something from starch at all.
The first link is basically an “advertisment hidden in a normal, professional-looking article”. All they’re saying is how these ways are not secure, but most importanly, how their solution is more secure, published under their own site.
When you take this into account, their claims start to break down: while yes, email and SMS MFA might be inherently less secure since the code could be transmitted via an insecure channel, saying TOTP is not not secure because “you device can be hacked” is a kinda bad take: if your device is already hacked, you’d have a much bigger problem: even if you are using security keys, the hacker would already have access to whatever service you might be trying to protect. As for the lost/stolen case mentioned in the article, if you put TOTP code in a password manager (as most would probably do if they’re doing this), that shouldn’t be a problem. The only way this would be a problem is that the TOTP secret is stored in plain text, which would be the same for any authentication methods.
Not Samsung, but I do have a Redmi 2 (also MSM8916) since I can get one for roughly $10.
On paper, the performance is closer to PinePhone (not Pro), and it would definitely be a lot less powerful than a PinePhone Pro running RK3399(S). They also typical has only 2 GB of RAM (some have even less), and that’s definitely going to be noticable. It should be fine for light use and thinkering though.
Some Samsung phones might have networking issues, and some might not even be unlockable, but I’m not really sure about it either, so definitely check before buying.
Also, not all MSM8916 is built the same - some works better than the other. Devices from the community category should be somewhat usable, but be ware of those in the testing category, since they might have major functionalities missing (e.g. touch).