That's definitely not true, Raspberry Pi OS works and acts like a normal Debian installation per default - with root mounted rw and all.
Other than that, there isn't much "treating like an HDD/SSD" going on, it just writes to flash when an application requests it does. If the underlying storage is an eeprom, an sdcard nvme storage doesn't really change anything here.
Most SD cards aren't really suitable for the kind of workload an operating system generates (that being mostly random i/o). Make sure to get a reputable A2 (application class 2) rated card, they aren't that expensive but perform way better.
Raspberry Pi themselves launched a card recently, I haven't tried that one but it's probably a good choice too.
This wasn't about arm in a high end laptop though, this is about underpowered cores in an soc probably meant for sbc applications barely managing out of order execution shoved into a laptop form factor.
I'm not against riscv on principle, in fact I quite like it. But let's not pretend it's performance is there yet for laptop-class devices.
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