As far as I know, there is no easy way to get something similar to Android’s Verified Boot on Silverblue right now. This a work in progress on several fronts (rpm-ostree with IMA/fsverity, Keylime, etc.) but note that due to the inherent freedom that Silverblue gives to administrator users on the system, this makes it much more difficult to get to the same level of security guarantees without scarifying freedoms like Android does.