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gravity-reprint While what you wrote is correct and maybe a heavily secured and sandboxed PDF reader can mitigate a dangerous pdf file, that was not what the OP asked about.
I also find your remark about how OP should install an OS before posting at the very least unnecessary, and at most disrespectful and patronizing because 1) you have no way of knowing if OP has the OS installed or not and 2) they have every right to ask questions about it without actually having it installed on a device (as many actually do the same here), that is what this forum is for I imagine. Hope you have a good day.
@kebab_definite maybe dangerzone has a CLI, in which case you might be able to make it work in a terminal emulator like Termux. But do note that Termux may not provide sufficient security regarding the program such as isolation.
The mat2 python metadata removal tool has an option to turn .pdf-s into images, but I don't know how that fares in regards to security, or does it actually make pdf-s safe.