Most people go with a trainer, but I went with the full indoor smart bike (Wahoo Kickr Bike). Not cheap, but I didn’t want to bring my bike indoors with an oily chain around cats and carpet. The bike does a pretty good job of mimicking the real thing, but it is overkill.
There are numerous articles/videos on how to get into Zwift at different price levels. One thing that is preferable for Zwift, especially if you want to do the workouts and the FTP test, you need a power meter. So if you get a trainer, I would get one that has one. Or of course, get a power meter for your bike so it’s usable everywhere. We have talked about it a little in the thread linked below.
On the bike computer I use a Garmin 830, but I am not familiar with the ones you mention. I use it for distance, speed, power, etc. I never use it for navigation so I can’t tell you anything other than I know it does have it. Wahoo’s computer seems to be the most popular nowadays, but there is a new brand called Hammerhead that seems to be growing in popularity.
DC Rainmaker is great for sports tech reviews, so I would check out his site for more info on all of the above.