one of the main reasons for the conversion to Christianity being how inexpensive Christianity is for lacking said practices.
Christianity was expensive too, if not in the same way. The amount of land the church would accrue over time that was tax free was shocking in some cases. While some places would eventually be able to push through tithes on church land, like England during the HYW, during war, for the most part this land did not pay taxes. The local bishops and archbishops could then use the money they accrue due to this to provide loans to nobles or kings in return for extended privileges, autonomy, and land. It was a self-serving cycle that propelled the church in multiple countries to major landholders with a disproportionate amount of power...Not to mention outright moving against the Church always placed someone at risk of excommunication or interdict. The Catholic Church didn't become corrupt from nothing, it very successfully accrued incredible wealth and power over time.
While a successful Saxon resistance against the Franks could delay Christianity, Saxony was bordering the core strength of the Franks. Unless the Franks suffer a downward spiral of power, at some point they'd be able to bring the bulk of their strength against the Saxons. To survive Widukind would need to create an alliance of multiple northern Germanic peoples. Maybe if the Viking Age started sooner there'd be Nordic kings willing to assist by raiding northern France, but how organized and coordinated any such resistance would be is debatable.
Actually against what a number of people have said, I don't actually think it is in regards to religion that advances need to be made. Although a more organized religion would of course help. I think it is politically that the Norse would need to organize. The Norse weren't organized even into proper kingdoms, besides Denmark, at the beginning of the Viking Age. Just petty kingdoms and localities. This prevented the sort of organized invasions Sweyn Forkbeard, Cnut the Great, and Harald Hardrada were capable of organizing. Not to mention coherent conquests and nation building, compared to the mere disorganized opportunism that characterized the early Viking Age. Even the Great Heathen Army was lacking in organization. Then even later, the loose and unstable succession laws of the Nordic kingdoms meant frequent civil war and usurpation. During such times, the claimants naturally looked outwards for allies. All too often Christians were all too willing to back claimants who have or are willing to convert. Gold to buy mercenaries, bribe nobles, and impress people with their wealth could be more than enough to tip the scales in their favor. These Christian kings then brought European/Christian ideals, methods of government, and ideals on kingship to the Norse. It isn't a coincidence that the Nordic kingdoms generally became more organized as they interacted with Christianity and became Christianized.
More organized Norse kingdoms earlier could have had more success in the Early Viking Age, hurting the Christian kingdoms more and lowering their prestige in the eyes of the Norse. They'd more easily be able to decide their conquests based on economics as the Christian kingdoms would eventually start using economic warfare to hurt them and force them to convert. An early use of this could potentially allow the Norse to focus instead on the eastern trade routes, to bypass western Europe. If this was done before Kievan Rus converted to Orthodoxy, you could potentially have these trade routes too well developed for the Rus to be willing to cut them off. More stable royal families for the Nordic countries would likely intermarry, creating the overlaps that allows personal unions and one kingdom having claims over another. A few marriages, convenient births or accidents, and chances of an alt Denmark-Norway or even a unified Nordic country are possible. If the mentioned ancestor worship mixed with Imperial Cult forms around said royal family, it would give them very good reason to oppose Christianity on principal. If nothing else avoiding the rise of people like Olaf Tryggvason, who spent most of his life not in Norway before becoming king, were able to brutally start Christianization would delay Christianization for potentially decades.
However I will state that a non-Christian Scandinavia would almost certainly become the object of an alt-Northern Crusade. The Northern Crusades were called because the Catholic Church had difficulty motivating Saxons, northern Germans, Polish, and Norse to crusade to the Holy Lands. Especially when there were non-Christian people right across the border. I don't see any reason for this to not happen with a non-Christian Scandinavia, unless you make it a full on Christianity screw where there's a major schism to distract the Christian kingdoms for centuries. So you'd almost certainly see Crusader states being carved out of Scandinavia.