I had a Synology about 5 years ago before truenas. It was fine. The main problem I had with it was the price for the quality of hardware. You could build a FAR better device for MUCH cheaper and load truenas onto it. Yes you have to figure a lot out yourself. And the support you have is forums. But people in the truenas forums are very helpful.

There are a ton of apps already ported over to truenas. Plex and unifi controller to name a few. Also immich for photos. And nextcloud if you're into that.

The one thing I found that Synology does much better is surveillance cameras.