The Verdict: Not eligible
The UK has no route for investment alone: buying property, funds or bonds does not give residency. If you would build and run a new business yourself, look at Innovator Founder; otherwise at Global Talent, Skilled Worker or the UK Ancestry visa.
Tier 1 (Investor), the £2 million route, closed to new applicants on 17 February 2022 and is not coming back.
A £5 million invite-only visa and a £250,000 Britannia Card have been proposed, but neither has rules and nobody can apply for either. Do not plan around them.
Innovator Founder has no minimum investment, but you must run the business yourself, and an approved body must endorse it as new, innovative, viable and scalable. Money put into someone else's business does not qualify.