Last year I made a website for my gf where I had to build a custom map of Paris, and I struggled a lot trying to figure out how to actually make a map from scratch while avoiding paid services like mapbox.
I finally managed to hack something up using openstreetmap data, then some manual work in QGIS to customize the look, and voila - I had a bunch of folders filled with raster tiles.
This site is deployed for free on Netlify and is basically just a React SPA, a public folder with tiles, and I give the tile URL template to the OpenLayers lib to display it all nicely on the screen. Simple and it works!
I always wanted to improve the map a bit by using vector tiles as I think it looks nicer, but I thought you need a dedicated server for that? (unless I'm mistaken, correct me if I'm wrong)