Mostly, no.
"You can request to have the annual Apple Developer Program membership fee waived if you’re a nonprofit organization, accredited educational institution, or government entity that will distribute only free apps on the App Store and is based in an eligible country."
"Fee waivers are not available for: Individuals and sole proprietors/single person businesses"
So I already pay the $100 a year. But there is a browser extension I help maintain that has a very limited audience (it is essentially an internal tool, though it is in the Chrome and Edge stores). I would like to bring it to macOS/Safari and started the process of doing it. But there are so many hoops, it will vastly change the build pipeline (I’ll literally have to package every single update differently than the other platforms), and the process is so convoluted that honestly, I’ve given up for now. Bear in mind, I’d be the primary user of said extension and even for me, I can’t make the internal argument to waste time doing it over just using Chrome or Edge when I need that feature.
Having said all that, I should go ahead and port it to Firefox. That at least is a lot more straightforward.
You have to explicitly grant permissions as a user for safari extensions.
I don’t know that effectively slapping an app shell around an extension is a big hurdle, but no other web extension store charges for entry, so that very well could be the real barrier here.