I want to make an item that essentially increases the base number of dice for healing spells by one. I can't figure out how to do it. Cant it be done right now?

You would have to do it as plain text and the player would have to remember to roll an additional die separately and add it to the total.

Is there a way to do additional healing bonus (in Homebrew) now that the Life domain cleric healing bonus is finished?

e.g. I have a "glove of the healer" which is intended to do an additional 1d6 for each healing spell.

Technically you always could, it just wouldn’t add the roll automatically. I think it is still the same currently as they still have the tools for the new programming locked out of the homebrewer as per the announcement post.

https://www.dndbeyond.com/changelog/960-cleric-life-domain-disciple-of-life-update