The OP's comment that the walk up to Somport was more difficult than that to Roncesvalles on the Napoleon does not agree with my experience.
In pure hiking terms, I'd agree -- getting over the pass itself is pretty simple, and it's a rather shorter hike from the bottom of it to the other side than SJPP > Roncesvalles.
What I did find more difficult was the monotony of much of the walk to reach the pass, enclosed as you are in such a narrow passage between claustrophobic mountain barriers on either side. (Of course, there are some wonderful places along the Way.)
Otherwise, for the Somport, I'd advise a start from Lourdes rather than from Oloron.
If you start at Oloron Ste Marie, you will be on the Camino d'Arles until you climb up to Somport Pass. That's fine, if that's how you want to do it.
IIRC the French GR waymarking ends, and the Spanish begins (yellow arrows !!) somewhat before the pass itself. And hmmmm, Oloron-Sainte-Marie > Puente la Reina has "official" names and so on, but technically it's still a variant route of the French Way. Spanish Camino maps in the 1990s showed the Ways to Santiago via both Roncesvalles and the Somport as the "
Camino Francés".
Somewhat similarly, the stretch between Zaragoza and Logroño is simultaneously part of the
Camí Catalàn, the
Via del Ebro, the
Camino Ignaciano, and of course, both the
Camino de Santiago and the
Via Romea -- and which of those it is for an individual pilgrim depends mostly on that pilgrim's own intents and purposes.
It’s not important … but I often read on forum posts and elsewhere that the Aragones joins the Frances in Puenta la Reina. I’ve walked the Aragones twice and the path joined the Frances in Obanos. Puenta la Reina is 2-3 kms further west. Unless I went the wrong way … twice! I only add this because if pilgrims are coming from the Aragones, they have the option to stay in Obanos or walk on to PlaR.
There are two options for joining the
Francès -- the most obvious one takes you to Obanos, but a variant does take you straight to Puente.
I didn't think about bringing lots of cash with me after Jaca. There were no ATM's so I had to abort about halfway and take a bus to Pamplona
There's bound to be one in Sangüesa -- and IIRC a few of the Albergues & restaurants etc. on the Way accept cards. (? Not really certain, as I was rather penniless on those days) But yeah, definitely carry a bit more food & cash than usual !!