As others have already said, Yom HaShoa is not an exclusively Israeli holiday. It's pretty common for American synagogues to have some sort of observance of it. There's no particular reason to expect it to be Passover-esque, since Passover's pretty much the biggest Jewish holiday there is.

There are liturgies for Yom HaShoah, which are generally modeled after other days of mourning. The usual one is lighting a memorial candle and reciting the memorial prayer in services, and perhaps everyone saying the mourner's prayer. There even exist people who observe the day as a fast, though that is liturgically problematic. There also are other additions to the liturgy less commonly included that do exist, modeled after fast days (I would give more details, but they're only in Conservative prayer books, which I don't have on the shelf).

Widespread acceptance and observance of all of the above is limited for a few reasons:

1. Fasting on Yom HaShoah is problematic because it falls during the month of Nisan, during which fasting is forbidden

• The Holocaust happened recently, and there's been little time for a ritual to coalesce
• Compared to other holidays (both happy and sad) that commemorate events, the Holocaust had limited (explicit or direct) impact on Jewish theology or practice
• There already are fast days that, while they explicitly are related to the destruction of the Temple, have already been used as catch-all days of remembrance. There was an explicit effort to do that with the Holocaust and the 10th of Tevet, one of those fast days

If you're interested, one such liturgy is here. It's important to note that it's extremely uncommon to actually use this particular liturgy (I have never even heard of a synagogue using it), perhaps you'll find it interesting. Usually it's just lighting a candle, everyone saying the mourner's prayer, and the memorial prayer, whose text is here. Here's a liturgy that's basically that, plus a variety of readings.