Begin by setting up your Google Cloud environment. If you haven't already, create a Google Cloud Platform (GCP) account. Once your account is ready, create a new project in the Google Cloud Console. Enable the Pub/Sub API for your project by navigating to the APIs & Services dashboard and searching for "Pub/Sub" in the library.

Within your Google Cloud project, create a new Pub/Sub topic. This topic is where you will publish the data fetched from CoinGecko. In the Pub/Sub section of the Google Cloud Console, click "Create Topic," give your topic a name, and ensure it's linked to the correct project.

To interact with CoinGecko and Google Pub/Sub, you will need to install specific Python libraries. Use the following command to install them:
```bash
pip install google-cloud-pubsub pycoingecko
```
`google-cloud-pubsub` is used for interacting with Google Pub/Sub, and `pycoingecko` is a Python client for the CoinGecko API.

Write a Python script to fetch data from CoinGecko using the `pycoingecko` library. Here is an example to get the current price of a specific cryptocurrency:
```python
from pycoingecko import CoinGeckoAPI

cg = CoinGeckoAPI()
data = cg.get_price(ids='bitcoin', vs_currencies='usd')
print(data)
```
Replace `'bitcoin'` with the cryptocurrency of interest, and `'usd'` with your target currency.

Set up authentication to allow your Python script to publish to Google Cloud Pub/Sub. Download a service account key from your Google Cloud Console. In the IAM & Admin section, create a service account with Pub/Sub Publisher role, and download the JSON key. Set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable to point to the downloaded key file:
```bash
export GOOGLE_APPLICATION_CREDENTIALS="/path/to/your/service-account-file.json"
```

Extend your Python script to publish the fetched data to the previously created Pub/Sub topic. Here"s a sample code snippet to publish data:
```python
from google.cloud import pubsub_v1

# Initialize a Publisher client
publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path('your-gcp-project-id', 'your-topic-name')

# Fetch data from CoinGecko
data_str = str(data)
data_bytes = data_str.encode('utf-8')

# Publish to Pub/Sub
future = publisher.publish(topic_path, data=data_bytes)
print(future.result())
```
Replace `'your-gcp-project-id'` and `'your-topic-name'` with your actual project ID and topic name.

To regularly fetch and publish data, schedule your Python script using a task scheduler. On Linux, you can use `cron`, and on Windows, Task Scheduler. For a cron job, you might add an entry like this to your crontab:
```bash
*/10 * * * * python /path/to/your/script.py
```
This example schedules the script to run every 10 minutes. Adjust the timing and script path as needed.

By following these steps, you will have successfully set up a process to move data from CoinGecko to Google Pub/Sub without using third-party connectors or integrations.