We've turned the long tail listing management on and off for clients for years, it makes no major difference in ranking on Google. Especially if you're doing it via aggregators. It's a brand protection play and a complete local seo optimization move that can give a competitive edge but not a fundamental we lead with.
If you're a brand new business just starting out I'd just focus on a top 10 set of search engines, directories (Yelp, Trip, Nextdoor + vertical specific) and map platforms. Do as much as you can on the top 5.
MomentFeed (my company) have bundles that sell long tail but it's a true optimization play to go out that long in 2021. We don't lead with it. If you're focus and budget constrained, definitely put the $$ into better review management and optimizing your own website for Local SEO before looking at the long tail.
There is no search traffic opportunity on Citysearch.com or Localstack or any of these other sites you'll see in these long tail vendor networks. Use SEMRush to see their high bounce rates also so what little traffic that is reported, majority doesn't make it past the first page. They also don't have high domain authority to even warrant a consideration that a citation there is meaningful in ranking (anything 70 or below I ignore).
Remember though, Local SEO is very competitive so to beat out your competitors you may need to match their efforts and find ways to exceed. Many big brands check the long tail box because their programs have been running that way for years and are now modernizing their approach by investing more in reviews, local web and local social.