This isn't really a question about computer usage, but rather what you define as productive, and this is a deeper question about the meaning and purpose of life. This is probably why you've struggled in retirement.
It's been said many times on this site, worth saying again: FIRE isn't about retiring to nothing, or what retirement police deem acceptably unproductive. It's about freeing yourself from dependency on paid employment. Some people choose to work side hustles or part time, or whatever they find meaningful. Others choose volunteer work. Still others fill their days with hobbies or doing nothing at all. It's choose your own adventure.
IMO, you need to flip the script on what it means to be 'productive' if you want to thrive in FIRE. Exercising is productive -- a way of caring for your most important asset, your health. Spending time with loved ones is *way* more important than making more money. Travel is a way to create unique and lasting memories. Hobbies are a productive way to have enjoyment, build skills, build community, etc. Gardening, doing the dishes, cooking, doing the laundry... all productive work.
In this way of thinking, computers are neither good or bad, productive or unproductive. What matters is how you're using computers and the purpose they serve in your life. For me personally, computing is a hobby I use to help others: setting up networks, debugging issues, refurbishing old machines to give them new life (and keep them out of landfills). I deleted most of my social media accounts because these were time sucks that weren't life giving. Similarly, I've taken steps to avoid Big Tech algorithms (using FreeTube instead of YouTube, Ground News instead of Google News, etc.). But there are a number of video channels and podcasts that I love taking in during the day. And I do "waste" time online because sometimes that's fun and relaxing. But mostly I try to prioritize people and relationships.