Here's a couple links to online sitemap generators. I know one of them is better than the other, but I don't recall which as I have an app that I use to create them through A1 Sitemaps app.
https://www.xml-sitemaps.com/
With this one, if you're using Windows it has a free app you can download as well: https://xmlsitemapgenerator.org/
These are both free with limitations on features, but they do the trick for what you need for SEO without having to bog down Bootstrap Studio. I don't know of any other HTML editors that contain a sitemap generator myself, unless they are something expensive and I don't even know any of those.
If you need a decent sitemap generator, then check out A1 Sitemap tool, it works pretty good and they have a lot of other apps that have lots of other features as well for SEO. I say all this because I really don't want to see this app become bloatware with things that just are not necessary for a site editor when there are many other options out there already. Spend a few bucks and get one that's already set up for that purpose. In my opinion (and yes, it's just mine lol) every app doesn't have to include every possible thing it could be connected to in it. That's why there are software programmers to create specific apps for specific needs.