Interesting pitch. On paper Finstel looks like another "pro stack" bundling a trade copier, multi-exchange terminal, copy/social features and white-label apps. That can be useful for desks that live inside API rate limits all day and don't want to duct-tape 6 dashboards together. A few things I'd want to see before trusting it with real flow:

You say non-custodial via API -- good -- but do you support IP allow-lists, key scopes, per-role API segregation and read-only by default? What is your blast radius if a bot token is compromised?
"Sub-0.5s order execution" across Binance/OKX/Bybit is highly path/exchange dependent.

Copy-trading and branded social Platforms are regulatory minefields in many jurisdictions. What is your stance on licensing and registrations and how do you prevent things like slippage games?

Do you have 3rd-party security review, pen-test summary, SOC2/ISO 27001 roadmap? Supply-chain controls for your bots and web extensions?

Performance-based is attractive, but in my opinion fee drag kills edge. Clear, capped pricing is better for pros.

If you can publish hard numbers (latency histograms, exchange uptime, failure modes) and a security whitepaper, you'll get more serious teams to kick the tires. Until then, I'd treat it as promising but "trust, then verify" -- start read-only, paper trade, then canary with tiny size.