Purchasing "authentic" backlinks or another way to improve rankings without spending too much time on SEO?

I'm developing a time tracker that's on the market for 10+ years already. Organic search on the App Store, social networks and organic search on Google are the main sources for my (new) users. I would like to improve the latter and specifically focus on a specific set of keywords. When looking at the competition for those keywords, it's definitely clear that many backlinks have been bought. For example, I created a better article than the article that ranks #1 and sent webmasters behind the backlinks pointing to that article an email asking if they are open to link my article instead. I got dozens of offers for guest posting and link inserts. This to me feels that purchasing (high quality?) backlinks still works despite this being bad practice. I'm an indie developer and have limited time and resources, so I have to pick my battles. Unfortunately I don't have the time to write high-quality articles on a weekly basis and manually reach out to webmasters to capture really "genuine" backlinks. Hence, I'm probably favoring exchanging money for time (at least for experimenting) but obviously it needs to pay back sooner or later. Even more important: whatever I do should not harm my existing rankings. Hence, I would like to avoid black hat SEO. I've always stayed away from purchasing backlinks but seeing my (higher ranking) competitors doing the same, I'm wondering if it's really *that* bad. So last week I had a conversation with Rhino Rank and it actually sounded not bad. What they say themselves: >Building links can significantly boost your website's performance when executed properly. Unfortunately, not all links or link providers manage to drive the desired increase in traffic or authority within a specific niche. At Rhino Rank, we're committed to bucking this trend. As we discussed, our speciality is securing authentic links through genuine outreach. We liaise directly with real webmasters/editors on websites designed for genuine readership, rather than merely existing as link platforms. Is it worth going this direction (at least for a while, to see how it goes)? Is it dangerous? Are there better ways to improve my ranking without spending days per week on SEO myself? Thanks for your advice!