Bottom line – MaxROMs.com positions itself as a free, community‑driven hub for Android firmware.
The gold standard. While not strictly legal in all jurisdictions, Archive.org is a non-profit library. Every ROM uploaded here is scanned for basic viruses, and the community curates the collections. Search for "TOSEC" or "No-Intro Collection" on Archive.org. This is closest to "verified" you will get.
Suppose you download Super Mario World from Maxroms.