In the 5th century, Roman Africa was conquered by Vandal invaders, and despite attempts by the Romans to recapture it, it remained Vandal until the 6th century and occupied by Muslim conquerors a century after that. The Vandals often get a rap for being savage and uninterested in culture and civilization, but this doesn't seem like a particularly nuanced depiction, and I assume it's not necessarily contemporary. So what was the culture of Vandal North Africa like? Was it culturally Germanic or Roman, or something else?
The first thing to note is that the Vandals and Alans were always a minority in North Africa -- Victor of Vita writes that they numbered around 80,000 men, women, and children when they crossed from Spain in 429. Procopius says it was only 50,000. The Byzantines retook the region in the 530s with an army of only 16,000 or so.
The accounts we have imply that the Vandals made some effort to hold themselves apart from the existing culture and religion of the region, and perhaps even felt threatened by it. Catholic priests were forbidden from preaching in Vandal settlements and Victor of Vita says that an Arian bishop insisted on speaking a Germanic language during a debate with Catholic bishops. After retaking North Africa, the Byzantines exiled the male Vandals, so presumably there was still a clear distinction between Vandals and non-Vandals at this point.
That said, many Vandal tombstones are in Latin and their rulers cooperated closely with members of the old Roman aristocracy of the region. And it's certainly not true that the Vandals were uninterested in Roman culture. Procopius writes that the Vandal king lived in the style of a Roman emperor and ate in the Roman style. The Vandal aristocracy seems to have enjoyed Latin poetry and activities like theatre and chariot racing and took Roman-style villas.
It's very hard to answer this question for sure (we do not have a ton of sources for the Vandal kingdom), but the sources we have suggest a fusion of cultures, with the Vandals becoming somewhat Romanized, while at the same time trying to hold themselves separate. Wolf Liebeschuetz writes that "Culturally there was compromise. Romans wore Vandal dress, leading Vandals took up the way of life of members of the Roman ruling class, including in some cases at least the higher literacy."
As an example of Vandal attempts to engage with the existing culture of North Africa, you may be interested in a proclamation that Victor of Vita says the Vandal king sent out challenging the Catholic bishops in his kingdom to a debate with his own Arian bishops:
Hunirix, King of the Vandals and Alans, to all the homousian bishops. It is well known that not once but quite often your priests have been forbidden to celebrate any liturgies at all in the territory of the Vandals in case they seduce Christian souls and destroy them. Many of them have despised this and been discovered to have said mass in the territories of the Vandals…And because we do not wish for scandal in the provinces granted to us by God, therefore by the providence of God and with the consent of our holy bishops we have decreed this: that on the first of February next year you are all to come to Carthage, making no excuse that you are frightened, so that you will be able to debate concerning the principles of faith with our venerable bishops and establish the propriety of the Homousians.
The resulting debate was a fiasco -- Hunirix claimed that the Catholics took it "upon themselves, with consummate foolishness, to throw everything into confusion with seditious shouting, with the intention of bringing it about that the debate did not take place." Victor claims that the whole event was rigged and that Catholic spectators were beaten up mid-debate. So it didn't go well, but, you know, they tried.