George Kadianakis:
An unfortunate exception here is v3 onion services: v3 onion services only tolerate skews of maximum ±3 hours [1] but in most cases even tighter than that. This is to assure that v3 clients and services have a recent and accurate view of the network. In theory all of Tor needs a recent and accurate view of the network, but v3 is particularly fragile because of the shared random value and the precise time periods.
Sorry to break the bad news, but it is what it is. In theory we could potentially do improvements for v3 here, but this is not in the scope right now.
Actually Tails should be fine: once Tor has bootstrapped Tails syncs the time using htpdate which should also fix v3 onion service access. So I believe intrigeri's questions were only for bootstrapping + creating a circuit to a non-onion end-point -- once Tails succeeds with those it *can* sync the time accurately.
Cheers!