43 amps on the Jackery vs 100 amps for a GP31 battery not much of a comparison. One could easily buy 10 years or more of Gp 31 batteries for the cost of one much less powered Jackery.
While I agree, it's not quite that clear cut.
The Jackery's Li-NMC battery:
Costs more per Ah
Weighs less
Can charge much faster
Doesn't suffer from partial charge cycles
Can deliver around 30Ah without harm
A Group 31 lead battery:
Costs less per Ah
Weighs more
Can take much longer to fully charge
Will be damaged by partial charge cycles
Can deliver around 50Ah without harm
From what the OP has said, a
flooded lead acid Group 31 (sort of) deep cycle battery makes sense. Put it on a good mains charger to bring it to 100% at least once a month, and it should last for years.
Several excellent articles on batteries & other things electrical here:
https://marinehowto.com/category/electrical/batteries/