Tried this, it's a nice sollution for traffic handling, since it's way more performant. I still had to switch, cause I'm relaunching my domains every 2-4 days. Generating static pages eats up a lot of performance - and disk space. That's why I switched to spintaxes, based on a seed wich is the whole url and I only need to create basicly the sitemaps (and a template per domain) on a launch or relaunch. While this takes perhaps 5 minutes per 1k domains with 5mio pages, it would take hell longer with static pages - and I don't want to know how many terrabytes this would fill up

That's why I use FastAPI, it's really high performant as a backend sollution - and I can directly cache the spintaxes in as an list (basicly an array in python) in RAM.
I'm doing this for some years by now and performance was allways my hardest battle. I don't know how much earnings I lost, because my system broke under the pressure or search engines ddosed me, but it might be perhaps a 6 diggit sum by now =D
For indexing - as said, I go mostly for bing. It's easy to create webmaster console accounts automated - basicly the same process like with hotmail accounts - and getting the API Code, with that you can handle everything. It's pretty much sitemaps, bing loves it's sitemaps

And while it seems small, we don't just talk about bing itself, but basicly every other search engine but google, since all are using it's index. And bing has a really strange mechanism, I guess it's their sandbox to handle the algo-paradox:
They randomly rank your crappiest sites for the most absurd keywords for a little time. I actually ranked for "Star Wars" on place 1 once. I don't know why. It's just weired. But exploidable. This is mostly the main income of the new domains, the monthly income is more google relatable. With some interlinking of the domains, google will start finding em by its own.
I tried to list em in search console as well, it did bring a push for sure - but there was too much manual work included, since google wants a mobile number every 3rd account (wich is not manual but kind of expansive compared to bing) and it uses oAuth wich makes the automated account generation kind of a pain in the ass.
I don't use any backlink tools. Interlinking partly, and all domains are dropped domains.