Is it really not safe to download .apks directly from developers?

I asked on Discord and people are basically telling me the only safe way to get software onto my phone is thru Accrescent or Google Play -- so basically, for most things, Google Play.

For example, Wireguard has an official apk for download: https://download.wireguard.com/android-client/

I have put in extraordinary effort to avoid Google on this phone so far. Unfortunately, what I'm hearing is that to get any software, even something popular like Wireguard, the only safe way is to give me phone number to Google?