I think a lot depends on how fancy your system will be. Can be done very cheap with a simple electric engine and a diy construction, or you can spend easily 40.000 USD on a fancy system designed for boats.

I think electrical engines for sailing boats are awesome for day sailing and for the more adventurous sailors, who like to use only the wind and have the engine purely to manouvre into small spaces. The main problem is usually the battery capacity, which almost never allows you to use the engine for more than a few hours.

A back up generator may provide an emergency solution, to extend range.
I think the best part about an electric engine is that you can actually use it to charge your batteries while sailing, but especially if you go diy you might need to pay some special attention to this.

You might want to check out sailing Uma YouTube for some inspiration.
Keep us up to date what you’ll end up doing