Simple answer is YES. Apart from being a digital marketer, I have spent last 2 decades in banks implementing large BI and Digital transformation projects. Now I own my agency to remotely run their digital marketing efforts.

I find this question very interesting. I started my digital marketing agency last year in September and the pandemic actually came as a boon in disguise. Instead of challenges, all customers (and a lot of non-customers also) realized that Digital Marketing is the way to go.

We added on average 2 customers every month after Lockdown ended. Revenues have tripled and the only challenge I am facing is to fill capacity.

Not sure how Clarity did it but I can suggest a few things anyway.

1- Have your business plan and marketing plan ready and aligned to each other.
2- Have a concrete digital marketing plan as part of your marketing plan. Following is an indicative set of steps you may like to consider.

Digital Marketing plan-
1- Once you develop a digital platform, have it tested for engagement quotient (CTR, CTA etc.) and bounce. Resolve on priority if problems are found.
2-Implement a comprehensive SEO strategy.
3-Have a definitive user engagement and inbound marketing strategy in place. Such platforms can't rely on impulsive buying by customers. Content Marketing may be considered.
4-Get an offline fanbase ready to onboard initial set of users.
5-Once ready, launch a multi pronged digital campaign. Launch SEM and SMM campaigns to pick up the number of users. You may like to consider your acquisition costs carefully here but expanding fanbase will definitely require some investment.
6- You are up and kicking with a user base. Launch your further initiatives now.

Assuming that the risk is managed and your own involvement is limited to only the spare time you can't productively employ otherwise, there are a lot of passive income avenues. But don't forget, to earn passive income, you'll have to invest either time/effort or money in consideration. Or else, they have unavoidable downsides. Here are a few examples.

1-Property Rental (Financial investment needed)
2-Youtube channel monetization (Deep expertise and fanbase needed)
3- Vacation getaway management(Financial investment and self involvement required). It's a full time job but doesn't feel that way.
4- Royalty (Write a book or sell a self developed mobile application)
5- Share dividends (this is as close to a 100% passive income as it gets. RISKY)
6- Bank deposit interest (NOT lucrative)