Having weak security on your operating system certainly isnt helping when there is some sort of exploit in a browser running on that system. The perfect operating system may not prevent issues inside your browser, but it may limit the damage these do. I feel like you suggest using Linux reduces security - why do you say that?

I would always recommend good old Debian for a mostly „it just works“ experience. You‘ll find debian packages for most if not all the things you mentioned. Alternatively you could go the steeper route and use an immutable OS like Fedora CoreOS or Fedora Silverblue for a more desktopy experience.

Hardware wise I‘ve been told the Intel NUC kits work wonders, or similarly specced boxes from Asia. You might get like 32GB RAM, a fairly recent CPU for <400€. Personally I‘m using a 12 year old Mac Mini until it dies, running debian.