For example, on Firefox:

1. Go to your search settings (or paste about:preferences#search into the browser)
2. Under search shortcuts, press Add
3. Name it anything, and add the link https://lemmyverse.net/communities?query=%s. I also recommend using a keyword (see below)

Then on Lemmyverse, you can hit the home icon in the top bar to add your home instance.

Afterwards, to find a new community, it is as simple as:

1. Open a new tab
2. Type @ followed by your keyword and then the search contents
3. Click on a community and have it open in your home instance

You could probably do something similar with your instance, like https://piefed.ca/communities?search=%s. Any big instance is going to have 99% of communities already added.