@per.buhre, no, I do understand you -- you do not want to use sulfite and are looking to use chitosan as a replacement. This is not going to work out as you hope.
Chitosan's primary use in winemaking is as a fining agent. Any antimicrobial properties are an additional benefit, but are not necessary.
Use of chitosan in amounts above what is prescribed for fining will produce negative impact on the wine. The source of the chitosan does not matter.
Chitosan will NOT replace sulfite, since chitosan is not an antioxidant. Antimicrobial is only part of what sulfite does; the antioxidant properties are actually more important. Wine is a preservation system, with high ABV and low pH inhibiting the growth of most microorganisms. If the wine is good when bottled, oxidation is the far greater danger, especially as the wine ages.
Try a limited test. Treat 1 gallon with whatever concentration of chitosan you want. Bottle that gallon and an untreated gallon, and do a blind taste test 6 months later. If you are satisfied with the chitosan treated wine, great! If not, you need another plan.
If you are consuming the batch within 2 years, you can try going without sulfite. IME wines without sulfite are often in decline after 1 year, and all that I've had were in decline by year 2.