Help! No Games working at all (GOG & Steam)

Hey everyone,

I recently received a MacBook Pro 15.4" 2015 as a gift, as it was no longer needed. Since I've always wanted to delve into Mac usage, I've been tinkering around with it, initially on High Sierra. Eventually, I came across OCLP and upgraded to Sonoma. I'm quite satisfied with its performance. Photoshop and Lightroom work as expected, making work enjoyable.

Now, I wanted to try out some graphically undemanding games like Stardew Valley and other smaller indie titles. However, none of them seem to start up, neither through Steam nor GOG. Interestingly, they run smoothly on my acquaintance's M1 MacBook without any issues. Is there perhaps a trick or fix that I could apply but have overlooked so far?

Thanks a lot!