The strength of the application will depend less on the number of activities you have completed and more on the quality, impact, recognition, and independent evidence behind them.
Your strongest areas appear to be your role as a first hire/founding engineer at a fintech startup, your open-source contributions to Kubernetes/Minikube, and your work with the local non-profit. These are potentially valuable because they demonstrate technical contribution, responsibility and impact beyond simply performing your day-to-day job.
For the founding-engineer experience, however, being an early employee or founding engineer does not automatically demonstrate leadership. Your evidence should clearly show what you personally led, the technical or business problem you addressed, the scale of your responsibility, and the measurable outcome of your work. A GitLab contribution graph or commit history can support the story, but it is unlikely to be sufficient on its own. Stronger evidence would show the significance of the projects and, where possible, include independent confirmation of your contribution and impact.
The key question is not simply how many contributions you have made, but what you contributed and how the project or wider community benefited from it. Merged pull requests, technically significant contributions, maintainer feedback, issue discussions, releases, or evidence of adoption can make this much stronger.
The charity work could potentially support OC2 (contribution outside your occupation) if it was genuinely outside your employment and you can document your individual contribution and measurable benefit. The open-source work could also be relevant, but the strength will depend heavily on the nature and acceptance of your contributions rather than the number of commits.
The MSc distinction is a useful background, but academic achievement alone is unlikely to establish the mandatory recognition criterion. Similarly, a paper awaiting acceptance should not be treated as a published research achievement until it is actually accepted/published. If your supervisor is also writing a recommendation, make sure the letter demonstrates their established expertise and gives specific evidence of your potential rather than simply confirming your academic performance.
Before applying, identify your two or three strongest achievements, document the impact carefully, and obtain credible third-party evidence wherever possible. If you can demonstrate a clear progression from technical contribution → meaningful impact → recognition/potential for leadership, the overall application will be considerably stronger. Overall, it would be better to review the actual evidence before giving a realistic assessment of how competitive the application is and which areas need strengthening.