Always start a side-project with a domain name. Use it to help validate ideas in the short-term but get the benefits in the long-term as your project develops.
1 Redirect it to another website
- Quick and easy to set up
- Share the link and get brand awareness
- Lose your brand once clicked
Example: ultimatedigital.tools redirects to a Gumroad page
2 Custom domain on a third-party platform
- Get some functionality (e.g., email sign-up)
- Keep your brand when clicked
- Limited design and functionality
Example: futureskills.info uses a Mailerlite landing page.
3 Address for a website
- Lots more functionality
- Lots more control over design and branding
- Costs more time and money
Example: rogerswannell.com uses WordPress.
As a project develops and needs more functionality you can move the domain name onto other platforms and take the brand awareness with you and any links will still work.
Whichever way your project goes, you keep the benefits of having used the same domain name throughout.