One patient Genshin Impact player managed to glitch their way into the new Inazuma region without completing any of the quests normally required to unlock it by repeatedly disconnecting from the internet.
i_managed_to_reach_inazuma_at_ar_9 from r/Genshin_Impact
We have Reddit user dezeadmf to thank for this discovery (as Polygon spotted). Players have long speculated that cryo characters like Kaeya and Ayaka could repeatedly spam their freezing abilities to build a bridge of ice over the sea leading to Inazuma, but without a workaround to the electro storm surrounding the island region, this solution was dead in the water.
However, as dezeadmf explains, you can apparently get through this by pausing the game when you hit the electro barrier, manually disconnecting your internet (or disabling the internet of whatever device you're on, though your mileage may vary with different platforms), and then unpausing the game to swim for a few seconds before reconnecting your internet. I have no idea how or why this would let you bypass the electro archon's natural barricade, but you can't argue with the results.
You'd have to repeat this process several times to actually set foot on Inazuma, and there are plenty of ways for it to go wrong. Dezeadmf says they spent nearly six hours trying before their successful hour-long attempt.
Dezeadmf managed to reach Inazuma at Adventure Rank 9, which is well below the level necessary for the story quest that lets you ride Beidou's ship to the island. In theory, this could be done as soon as you unlock Kaeya and his cryo ability – or alternatively, at least for now, the ability to Wish and obtain Ayaka on the current banner.
Of course, beyond testing the game's limits, there's no practical reason to do this. Without completing the quests that lead to Inazuma, you won't be able to complete much of anything within the region, so you'd basically be nothing more than an under-leveled tourist. You've got to applaud the determination on display though.
Speaking of early access: this leaked Genshin Impact Aloy gameplay reveals how the Horizon lead fights in another world.