There's a nice archive of many of the popular computer magazines - including PC World, MacWorld, MacUser, Byte - available here: https://vintageapple.org

Over the past few years, as magazines have gone from print to online-only, I've subscribed to some of them via Zinio ( https://www.zinio.com ). They carry PCWorld, Maximum PC, Macworld, MacLife, and more. Their "reader" is nice, but I do wish it supported downloading the magazines as PDFs.

One magazine that is available in print and online is MagPi magazine ( https://magpi.raspberrypi.com ). Its emphasis is on Raspberry Pi. You can download back issues for free, and the print version is often available at bookstores such as B&N.