Battery maintainer sizing

[Ashful]

Thinking of just buying this unit. Not sure if it's the best, not really interested in making a science project of this or investing a ton of time in it, and this looks like something I could have up and running by this weekend:

Amazon product ASIN B08GXBH1QP

 

[ABMax24]

Victron Smart Solar 75/10

Any solar panel that outputs more than 18 volts. I just use the local guy that installed my house panels, usually they give you a deal to sell the last panel of a discontinued model.