NEW RELEASE: MacOS v1.0 Port of Summer Memories+ 2.03.10-Unofficial
Includes the game with a pre-modded save. Made for ARM (M-series) macs. Unofficial version made by Kin-Kun, and was ported to MacOS by me. Hasn't been heavily tested, there are likely bugs. Feel free to pin this download to main post. If the app doesn't open for you, follow the instructions in the README to remove the quarantine.
I also have an iOS version of Summer Memories. It requires you to sideload an .ipa file in order to play. If there's enough interest, I'll release it too.