Was there no requirements to get Plat Visa from OP? As I remember it, there had to be substantial business with OP to get it (Omistaja Plus or something like that).
No such requirements at least nowadays. You don't even need to be Omistaja-asiakas to get OP Visa Platinum.
However, to be eligible for this zero fees until end of 2024 campaign, you do need to be Omistaja-asiakas, which anyone can become by paying the fee, which for most OP banks is 100 EUR. And you can get that 100 EUR back in future if you quit using OP.
And to become Omistaja-asiakas, you don't need to use OP as your salary account, have loans or investments, or anything like that.