Fcitx5 is the best for Chinese. Honestly very impressed that there is a open-source keyboard this good for Chinese. Only thing missing is fat finger error correction (like autocorrect but it works on the preedit text instead of text already output)

I used to use Gboard for Cantonese input. I downloaded fcitx5 reading your comment and tried it for some time. There are some features noticeably missing compared to Gboard.

• top numeric row
• single-hand mode
• simplified and traditional characters selection#

# Found it. It's in the settings bar at the top of the typing area. Click it open and go deep inside it.

What Gboard and fcitx5 both don't have for Jyutping input is glide typing. I wish fcitx5 have it because it is really what could make me switch and not look back. Gboard in general has better finger tap detection/correction because duh Google had more data to train on. But I will definitely start using fcitx5 because being open source is sufficient for me to switch.

For languages that isn't supported by its plugins like Japanese, I have to keep using Gboard though.