Barcelona needs to try their best in order for them to win Osasuna, otherwise, they'll have to fight till the end of the season on pressure to make sure Madrid does not take over them. I feel this is the best opportunity for Barcelona to widen the point gap, because we don't know the unforeseen challenges that might come up in future before the end of the season. It's an important match for Barcelona.
The game against Osasuna tells how Barcelona is going to stay strong leading the table, previous game against Osasuna took them for the biggest number of goals recorded against Hansi Flick, 4 goals were scored against Barcelona, the game ended with Osasuna adding up the 3 points. Barcelona is to realize that this game to be played means to them great deal, if they want the title then they have to win this game, sharing points with Madrid isn't the best place to stay on the table, they will still be on top but it won't be easy on them if the Champions League game begin and they have to compete intensively on both competition when they supposed to be adjusting their players to maintaining the lead instead of fighting for the first position.
I don't think the match between Barcelona and Osasuna can be used to measure anything about the Barcelona because Osasuna are no match to them in any way. It will just be one easy match that Barcelona will use to increase their goal scored incase then end the season with the same point as Real Madrid, then goal difference will do the magic. In other words, Barcelona will win the match with that low odd of 1.25 and I expect them to score many goals as well, which is what I will measure their success with based on what I already stated before.