I agree with the above, a pony4 with Bafang BBS02 (with 250W sticker) and Rohloff intermediate gear. Nose 1.4 for weather protection - lots of sun on the Meseta... A solar roof is easy enough to adapt. Wide (and strong) BMX rims laced with Sapim Strong spokes and Schwalbe Crazy Bob tyres could possibly work. The Crazy Bob is as close to a moped tyre as you can get with a bicycle tyre.
If I had the money for a Rohloff then Agilo would quite possibly find the way to Santiago - double chainring (even on the road in Spain the gradients are pretty wild in some places) and... no motor. Only the rich pilgrims ride horses, others have a donkey for baggage but personally I would walk (the rest that I have not walked so far) or ride a velocipede without assistance. In fact I was looking at my credencial yesterday and the stages from Zubiri to Finisterre
Things have changed a lot since 2020 and the capacity of albergues is reduced greatly. Do not tempt the trip during Spanish school holidays unless you plan on camping. Do not plan on being there for the feast of Santiago... If things evolve positively I hope to be leaving from Zubiri at the end of September 2022 and continue with my plan - a marathon a day but this time I will rest for 2 days every week... So far I have averaged 38.6 km walked per day with a swollen leg from day 2, I stepped in some nettles to avoid being run over by a speeding car...