I’m assuming you’ve already increased your solar panels to the max. That’s a much better first step, in my opinion, than using a power “generator” as a first step.
After first boosting my solar to 335 watts and upgrading to a Victron solar controller many years ago I added a portable power bank to the boat in 2024.
There are several well known power “generator” manufacturers including Anker, EF Ecoflow, Jackery, DJI and Bluetti. Each brand has its own strengths and weaknesses. I went with an Anker SOLIX C1000 for its small size, portability and my specific power needs. Your power needs are probably different than mine.
I’d think about how big/heavy is your upper limit, where you are going to store it when not in use and then pick a manufactures model that has the other features you prefer. Be sure to consider after purchase customer support as well as that varies a lot between brands.