https://forum.obsidian.md/t/obsidian-for-windows-1-6-5-insta...
Im not sure how it differs technically from macos universal binaries but the user experience is basically the same - one download no matter what architecture you are on.
This only works if your installer framework (InstallShield, MSI, Wix, Advanced Installer, ClickOnce, etc.) supports such a trick. If it doesn't, you're forced to ask users on the download page which version they want.
If the users guess correctly, it's great. If the ARM users guess x64 incorrectly, it still works. If the x64 users click the ARM version by mistake, they will be greeted with a warning, from Windows, saying this software does not work on their device. This is technically correct but a conversion killer. The odds of this happening are also much larger than 1%, in which case, offering an ARM download is actually likely to be financially harmful on a business level.
(The smartest way of handling this I've seen is to only offer an x64 download, but your app's auto-updater "updates" your app to ARM in the background as though it were an app update. Good luck convincing developers to write all the logic for that though, on top of an existing most-likely-third-party update system, for such a niche market.)