Just like on PC and server, Linux on a smartphone has multiple distributions.
The most obvious difference are the package manager, release model, and file structure.
For example, Debian has a new major release once every 0.5~5 years, Ubuntu is every 6 months or 2 years for long term support, and Arch and Manjaro doesn't have major releases at all.
But for security and/or privacy, you might look for whether there are hardware kill switches (in the case of Pinephone and Librem 5, they have), what exactly they kill (Librem 5 might be more secure), etc.
When it comes to software, sandboxing is a good point.
Look at Qubes OS for example, where every app runs in its own isolated virtual machine.
The trade off is usually performance.
The reason why Ubuntu Touch has more security is probably because it's been existing for much longer than Phosh, and has a much more bigger and active community than Plasma Mobile.
All other Linux distro are in development, but Ubuntu Touch is more mature.
However, Ubuntu Touch doesn't run desktop apps, and you're often stuck with HTML5 apps.
It has a VM built in for desktop apps, but it's hard to set up, often doesn't work, and drains battery like an idiot.
But what I said previously is basically you don't need to pick a secure OS, you need to operate an OS secure.
Usually we Linux users pick an OS that is best for its purpose (for example, I pick Debian or CentOS for server soft (Debian for websites running modern technology, and CentOS for ancient websites and customers refuse to change), Manjaro for my own PC, Linux Mint for PC of friends who are new to Linux, etc).
Do you even need app isolation if you're already careful?
Do you even need app isolation if you know how to avoid malware?
A computer user is both the best anti virus and the worst exploit at the same time.
I've seen so many times when people would use Tor to go on Fakebook, and upload photos of clearly the street they're living in, or chat with all their friends they usually chat with.
In that case, the ultra secure Tor browser will not help at all, and you might as well just use Google Chrome instead.
As I said, you can hide from big tech with Linux as long as you're using a computer securely, but you most likely won't escape your carrier, and you definitely won't escape your government + 3 letter agencies (Clowns In America, No Such Agency, etc).
The most obvious difference are the package manager, release model, and file structure.
For example, Debian has a new major release once every 0.5~5 years, Ubuntu is every 6 months or 2 years for long term support, and Arch and Manjaro doesn't have major releases at all.
But for security and/or privacy, you might look for whether there are hardware kill switches (in the case of Pinephone and Librem 5, they have), what exactly they kill (Librem 5 might be more secure), etc.
When it comes to software, sandboxing is a good point.
Look at Qubes OS for example, where every app runs in its own isolated virtual machine.
The trade off is usually performance.
The reason why Ubuntu Touch has more security is probably because it's been existing for much longer than Phosh, and has a much more bigger and active community than Plasma Mobile.
All other Linux distro are in development, but Ubuntu Touch is more mature.
However, Ubuntu Touch doesn't run desktop apps, and you're often stuck with HTML5 apps.
It has a VM built in for desktop apps, but it's hard to set up, often doesn't work, and drains battery like an idiot.
But what I said previously is basically you don't need to pick a secure OS, you need to operate an OS secure.
Usually we Linux users pick an OS that is best for its purpose (for example, I pick Debian or CentOS for server soft (Debian for websites running modern technology, and CentOS for ancient websites and customers refuse to change), Manjaro for my own PC, Linux Mint for PC of friends who are new to Linux, etc).
Do you even need app isolation if you're already careful?
Do you even need app isolation if you know how to avoid malware?
A computer user is both the best anti virus and the worst exploit at the same time.
I've seen so many times when people would use Tor to go on Fakebook, and upload photos of clearly the street they're living in, or chat with all their friends they usually chat with.
In that case, the ultra secure Tor browser will not help at all, and you might as well just use Google Chrome instead.
As I said, you can hide from big tech with Linux as long as you're using a computer securely, but you most likely won't escape your carrier, and you definitely won't escape your government + 3 letter agencies (Clowns In America, No Such Agency, etc).
母語は日本語ですが、英語も喋れます（ｒｙ
