The first thing you're warned about by others when you develop a chronic or long-term illness is that people will forget you.
They don't mean to. We call them social cues for a reason. People often need a hook to get to thinking about someone, an excuse to contact them. We can all kinda keep up with injuries or acute illness because there are known dates and timeframes involved. Here's when to send flowers, here's when to drop off food. When you ask how they're recovering, you expect some sort of motion.
When you're sick on a more long-term basis, I guess you stop reaching out because you run out of things to talk about... "that fresh pillowcase sure was nice," "I liked today's third random movie better than the fourth." It's difficult to make new friends or sweet-talk existing ones into new, easier forms of communication without the energy to connect over a shared interest or ability to sustain a real-time conversation. You want company and friends, but it's hard to get people to engage open-endedly and asynchronously. They'll think you are tired and want to be left alone. But what you'll want is comfort and certainty in your connections.
Anyway I have no real point; it's just sad and it's universal. And a lot of people with chronic illnesses are still on full lockdown and lonely or have newly become ill without the benefit of the social support they'd ordinarily have to adjust to drastic changes in lifestyle or ability.
If you are lucky enough to be healthy and want to do something really awesome for someone who isn't, put someone you care about who you know is ill in your calendar and reach out consistently. Send them regular little notes about what is new with you, send uber eats to their door with breakfast on weekends, suggest something for their reading list or just send them some books if they're able to read comfortably, ask if you can pick up anything for a hobby they can still enjoy while you're out, send them a copy of the photos you take that are fun or pretty that you're not putting up anywhere.
Anything. Just... make it recurring. Each text or DM or "I saw this and thought of you" is a treasure.