Apple has a switch tool in the Play Store that helps Android people switch to iOS. It's unlikely Google would get such an app approved by the Apple bots in the App Store. However, it's done a bit of an end-run around that with an update to the Drive app. You can now back up your iPhone data to Drive, then restore it all on Android.

The new backup option in the iOS Drive app is found under menu > settings > backup. It can grab your contacts, calendar events, and photos/videos, uploading them all to Google Drive. The photos and videos will obviously take the longest, possibly as long as several hours if you have a lot of them. You will also need to be on WiFi for the backup to take place, and the Drive app has to stay open. Sadly, there's no SMS backup option.

When you log into your Google account on a new Android phone, the data from iOS will automatically be accessible in the corresponding apps. Just like that, you're in the Google ecosystem. This works with any Android phone, unlike the Pixel-exclusive cable transfer tool.