I know exactly what you mean because I had the same issue when I wanted to follow the Swedish hockey league and some second division football matches. What I found is a site that actually organizes everything clearly, so you can filter by country or league without having to scroll endlessly. The coverage is surprisingly broad, and they update odds quickly even for smaller events. The interface is straightforward and you do not have to jump through hoops to find what you are looking for. I have been using https://www.dubibet2000.com/en/ for a few months now and it has been a solid option for both mainstream and niche sports. They also have live betting for many of these leagues, which is not always the case on other platforms. The mobile version works well too, so I can check things while on the move. You can browse without signing up, but if you create an account, you can save your favorite competitions and get notifications when the odds change significantly. It has made following my less popular leagues much more enjoyable.