Here’s my take on this. First of all, in terms of Gaelic deities, there wouldn’t say anywhere in the texts, “so-and-so is the god of travel,” because that’s not the way it works with Celtic myth. So what we’re left with is deciding associations based on what they do in the myths. In that light, still only insofar as Gaelic gods go, your best bet for this sort of thing would be an animistic deity; in this case, specifically, you’d be looking for an animistic deity of a road or something of that nature. Here’s the problem with that: people build roads, they don’t form naturally, and therefore there can’t be legends about them forming supernaturally. All of the legends we have about animistic deities—Boann, Sionann, Aine; all of them created in some way the landmark that they are said to be the goddess of.
I’m not sure if things are different for Brythonic deities, but I rather doubt it. Your best bet, I think, would be a continental Celtic deity, because, quite frankly, travel is somewhat more of a big deal when you’re not on a tiny little island.
The thing about that is that, while there are local gods of specific roads, there does not seem to be any singular travel deity who rises to the top. This is due to the vast richness of Gaulish cultures combined with the overbearing influence of the Romans. Many, many Gaulish deities were identified with Mercury, who is the Roman god of roads and travel, amongst other things. However, because he is the god of many other things, it’s not always clear why one particular local Gaulish god is identified with him. In a lot of cases the Romans just went, “aww, look Gaius, they’ve got a little Mercury cult! aren’t they cute?” “They sure are, Gaius.” Even if you did fish out one or two (invariably Latinized) names that are definitely road-gods, all you would have would be the name. I can give you one right now that I dug up, Cimiacinus, but I’ll be damned if you can find any information on him.
Here is the inscription that he is known by, from Ludenhausen: DEO MERCVRIO CIMIACINO ARAM TVRARIAM M(ARCVS) PATERNIVS VITALIS QVI AEDEM FECIT ET SIGNVM POSVIT V(OTVM) S(OLVIT) L(IBENS) L(AETVS) M(ERITO) DEDICAT III KAL(ENDAS) OCTOBR(ES) GENTIANO ET BASSO CO(N)S(VLIBVS). This doesn’t say anything interesting, it essentially just reads, “Marcus Paternius (some Roman dude) made this temple…” on a certain date, etc. etc., “for the god Mercury Cimiacinus.” Aram is altar, turariam could be something to do with incense, but I dunno. There’s no information.
TL;DR Yes, there were many, but they are all local Gaulish deities and therefore there is little useful information on them.
I hate when black clothes are a slightly different black and don’t match
we joke but this is an actual thing
Don’t forget green blacks, blue blacks, purple blacks, that weird grey/black bullshit…