This is less like buying a bigger car and more like upgrading the stereo in the car - 256GB in 2025 is somewhat akin to having only AM radio, and I've found it gets annoying real fast when doing anything serious.
I would hesitate to put anything smaller than 1 TB in something that's supposed to be a daily driver.
On a more serious note, as others have said, you'll probably burn through these weird storage limitations quickly.
Also, what do you mean by "sensitive matters" on Mint? Because almost any way you spin it, I feel like it's not a great idea:
Also, as I said in another comment here, please upgrade that drive before you put a lot of data on it. If you don't and you run out of storage later (a near-certainty on 256GB), you'll have to go through the effort of getting everything copied, which may include equipment purchases and several hours of your time when you could jut do it right now while your important files are still small enough to fit on a flash drive right now. Save yourself the future trouble.
Anyhow, I wish you happy Linux usage.