Adding a review as there isn't one at the time of writing.
First off, I am absolutely shocked there is no review for this card, it is an incredibly powerful, archetype-defining and all but an essential auto-include in every Arissana Rocha Nahu: Street Artist deck you build. And, I assume it will only become even more important with Dawn as Ika rotates, and Living Mural is forced to take its place.
Once per turn, you can bounce a non-virus trojan back to the grip (so no Chisel, Botulus, Tranquilizer or Physarum Entangler) and gain 2 hosted credits on the UAV, which can then be spent on installing cards. Usually in Arissana decks, you will be continually installing cards from the start of the game to its end and since we can save up credits unlimited with impunity (unlike the companion Paladin Poemu) we can potentially spend multiple turns saving up and then make one big install. The lack of limitation on how these credits are spent makes me comfortable treating this as just functionally generating 2 credits per bounce.
In this way, UAV offers you the ability to do two things simultaneously:
Generate 2 credits per turn (2 drip)
Bounce an installed Trojan back to hand for repositioning (or to carefully manage MU)
2 drip, with no frills, is incredibly powerful, and the fact that this card can stack (once again unlike Paladin Poemu) means you can potentially drip up to 6 credits per turn.
Here is a list of all non-virus trojans in standard:
0 credits to install:
1 credit to install
2 credits to install
The only 3 cost card:
Almost a third of these net you the full 2 credits in profit, another 4 net you 1 credit, 2 more pay for themselves and only Living Mural will actually cost you money to continually bounce. Combine these with other effects like DZMZ Optimizer and you can pretty consistently profit that 2 credits drip per turn. On its own, 2 credits drip per turn is already extremely powerful and if you have 0 cost Trojans installed you probably want to be trying to bounce them every turn to maximise the possible profit.
Add to this the fact that Arissana can install a Trojan mid-run at no cost and you don't even have to spend a click installing a program to be able to bounce them back all over again. Add to this the fact that LilyPAD lets you draw a card the first time you install a program each turn and you realise that once per turn you can install a program at no cost, not even a click, draw a card for free and then bounce it back for the full 2 credits profit with impunity.
However, the real creative tool is bouncing the Trojans themselves, to allow you to regularly reposition them as needed, only Ika and Hush move themselves, everything else needs Spree or UAV to reposition them, and you will need to reposition them, as locking all of your Trojans into a single configurations cripples the creative adaptability that defines Arissana's playstyle.
Combined, Urban Art Vernissage is both a potent econ tool and an essential flexibility tool to allow you to constantly reposition your collection of Trojans where they are most needed.
The reason why I think this card will only be more important soon is that while most current Arissana decks utilize Ika as their Killer of choice, Ika will rotate with Dawn and unless a new Trojan Killer is released in Dawn, Living Mural will probably become the breaker of choice. Living Mural, unlike Ika, cannot reposition itself, making it all the more dependent on UAV to pick it up and reposition it, plus the Threat 4 text makes it stronger whenever it's installed, further rewarding you for constantly bouncing and reinstalling it.
Thematically this card is probably just a reference to the fact that Arissana is a street artist who likely has a day job managing an Urban Art Vernissage. A vernissage is just a French word for a specific type of art exhibition. As for the quote... I tried to search for what Gemeosianism is, let alone meta neo-Gemeosianism but my search results came up empty which leads me to believe it may just be a fictional term invented by the card designers/narrative team.
The first two adjectives/prefixes are pretty straightforward and commonly used in art parlance, neo- just means new and meta means with or after or sometimes beyond, it's from the Greek of course, in otherwise words with or after neo-Gemeosianism, sometimes beyond neo-Gemeosianism (I really hope that someone gets this joke lol!). It's entirely possible that Gemeosianism is a nonsense word used to make a light joke out of artistic jargon but if it is more than that and anyone can drop a comment below referencing what Gemeosiansism is meant to refer to in-universe that would be much appreciated!
TLDR: a really strong and incredibly valuable card that is the lynchpin in Arissana's Trojan-based strategy, if you are playing Arissana without this card and wondering why your deck feels clunky and difficult to use, please add this card, it will make your life so much easier.