Is there a software/service that lets me see & test my app on multiple Android/iOS devices
Check out appetize.io. Their trial plan gets you 100 minutes a month and it’s pretty reasonable after that. You can download builds direct from expo on your https://expo.io/@<username>/<project-slug>/builds page, upload them, and run.
Note: To build an iOS simulator build you’ll need to run expo build:ios --type simulator. Android is just the apk from expo build:android.