How to charge money for a side-project web app?

I'm working on a web application, albeit one that runs locally on a user's computer and doesn't use the internet. I saw a pain point in a niche audience and realized I could fix it. My initial thought was to make the project open source. Then I could put something up and get feedback and people might appreciate it. Two people I trust who've looked at the project suggested that I really should sell it, so I'm considering that. ("Why not both," you may ask. I'd be happy to take pointers on selling software to consumers and also providing the source.)

If the project is open-source, I can just put up a website that people can access and use it. I don't expect the hosting to cost much.

If I'm going for commercial software, things get more complicated quickly (even not accounting for the fact that the relationship with the audience is different; what they might appreciate as a useful tool shared with them would need a lot more polish and testing to be something they are happy to buy.) I see two main approaches: running a SaaS application (ie. where users need a login, and probably pay every month for access) or producing a series of apps for different platforms (probably using Electron and Capacitor) which can be sold through app stores (although may require IAPs, sigh).

For a SaaS-like approach, I'm obviously googling the wrong terms; "Selling web-apps" is particularly bad. There's got to be a solution that deals with billing and knowing if accounts are in good standing that I can integrate. Everyone's got to do this and it seems a bit much to do it from scratch. The big perk of this approach, though, is that a user could use multiple devices with one subscription, including older devices if they support recent enough browser technology.

There is an appeal with the multiple apps in app stores as an approach. Namely, I don't have to worry about how to collect money from people and they don't need to log in to use the app. It just runs. As an additional plus, it makes people feel comforted knowing that their access won't just be turned off, or that it can run offline. The big downsides are that 1) I know people in this niche use "spare" computers (running older operating systems that you can't ship new store apps for), and 2) it is probably not so bad to create apps for major ecosystems and stores, but for lesser ones (where an online web app would just work) it just isn't going to be worth the time. [The pre-app-store approach, of needing a license code, might also be viable, but more effort.]

Let me add a couple of points here. I'm not really interested in running a business. This is more of a side project. If it isn't hard to serve an under-met need and make a little bit of money doing it (the much-talked about "passive income" approach), then that's great. The audience, while niche, is surprisingly large. If I do release a functional open-source version that people can just access through a website, I don't see that anyone would pay for a commercial version. (If they had to set up an `npm` environment and run it, even if I gave clear instructions, I think a commercial alternative would be viable.) I suppose I could put up a "tip jar" but my expectations are pretty low for such a thing. I don't think this is something that would be amenable to selling content via patreon or selling support, although many members in the audience are non-technical.

I'm grateful for any insights.