Transportation to Fusina port and lodging near that departure location (in Venice)

It's possible to take a land taxi from Piazzale Roma to the Fusina terminal. Look for a hotel within walking distance of P. Roma.
Google maps will also show the public transportation modes- ferry from the Zattere Gesuati dock in Venice, or buses (with changes) from Piazzale Roma.

You can also take a ferry from Venice to the cruise port. It leaves from the Zattere Gesuati stop in Venice and I THINK it goes directly to the cruise terminal, but I might be wrong. Try several google searches and see if you think that would work for you.

As TC says, you can take a ferry from the Zattere, ferry line 16. It is a 25 minute trip across the lagoon.
Get the app Chebateo for planning vaporetto (water bus) trips in Venice.

Too bad that app doesn't recognize Fusina as a stop, nor does it show a line 16 !

Did the OP ever make the trip?

Other cruise lines are offering this page as solid advice for getting to the port. Very frustrating that the only answer here is "I think so".

Did the OP ever make the trip?

the original post says that the "cruise [is] leaving on 10/20/25". That is October, 4 months away, and a week.

go to the official Fusina Terminal website (inked from the ACTV website as other operators) https://www.terminalfusina.it/en/navigation/lines#line-fusina-venezia and scroll down to the blue coloured Linea 16.

Note that it goes to the Terminal where the huge car park is - I don't know how far that is to the cruise ships, and also note that all ACTV tickets are NOT valid on the 16. Not single tickets, not multiday tickets, not Venezia Unica passes. Seperate tickets only, 10€.

Too bad that app doesn't recognize Fusina

it is not an ACTV service. Only ACTV services are on the CheBateo? app.