Can I gain Piety from multiple Diety on Theros?

There is a character in the Theros Beyond Death MTG cards who appears to have gained Piety from two deities at once, Eutropia, the twice favoured.

Her flavour text reads:

Nylea speaks to her in the windblown leaves; Thassa in the rushing tides.

Is it possible to replicate this using the piety rules?

The closest the rules text sems to get on this is:

If events in your character’s adventuring career warrant doing so, you can abandon the service of one god and turn to a different one. Once you abandon a god’s service, you can rarely go back without performing some act of contrition.

Your DM decides whether your new god will accept you as a champion and what you might have to do to prove your commitment.

When you change gods, you lose all the benefits granted by your old one, including rewards for piety and any other divine blessings. You no longer have a piety score to your old god, and your piety score to your new god starts at 1.

But it doesn’t cover having the favour of multiple gods at once.

The Renown system (which is similar to Piety, according to Is the Piety system restricted to only the deities of Theros?) from the DMG says:

A character gains gains piety for honoring his or her gods, fulfilling their commands, and respecting their taboos. A character loses piety for working against those gods, dishonoring them, defiling their temples, and foiling their aims.

emphasis mine

THe question I suppose is, is it possible to work for multiple gods without working against either of them at the same time?

Does piety work across planes?

Mythic Odysseys of Theros introduces the concept of Piety:

The strength of your devotion to your god is measured by your piety score. As you increase that score, you gain blessings from your god.

Nowhere does it mention if this is limited to a character’s presence on the plane of Theros, where the gods reside.

While the source book doesn’t mention moving between planes, is there any indication that this piety stops if the characters leave that plane? I’m asking in the context of the Magic: the Gathering setting where interplanar travel is possible.

My default assumption is that it’s unspecified and possibly unanswerable, but I’m happy to be proven right/wrong.

Is the new 5e Piety system restricted to only the deities of Theros?

The new sourcebook Mythic Odysseys of Theros includes the Piety system that allows the player to earn buffs and abilities depending on their relationship with their deity. The book defines all of this for the deities added in the update, but I was wondering if there are official rules for applying Piety to the existing Pantheon. I’m sure if there’s not, there will be homebrew, but just checking if the official rules contain it and I’m just missing it.