Reviewer (Scientific Expert) for the EU (since 2009) here.
The probability of getting a Horizon Europe grant allegedly (not official stats) is about 8.5% according to some friends, which may seem low. You need to write 70 pages following a Word template and the key goal is to cover answers to a large number of questions. Each proposal gets various grades across a range of dimensions, which get added up and if you obtain at least 13 out of a possible 15 points, you are eligible to get funded, read: "You will get funded if there is enough money." Often, there are several proposals that justly achieve 15/15, and because of that, many prosals that have 14 points and all proposals that have less may not get funded, simply because there just is not enough total funding available to fund all the technically eligible proposals. Having judged many proposals in AI / ML / search / "big data" / language technology etc. I recommend optimizing recall, i.e. aspiring completeness.
The application process is not easy, but you can get help: there are support agency in each member country, free online Webinars to help, hotline help desks as well as an ecosystem of paid consultants that typically charge about 3k€ to vet a proposal for you if you need that kind of service (I never used it).
The process is neutral and conducted professionally and with external oversight (consultants are hired as "rapporteurs" that report on process/procedural integrity in additional to the actual reviewers). I value the research officers of the EC as people of high competency, integrity and motivation (research money is tax payers money so it should be spent carefully).
In comparison, VC (and even more so business angel) funding is achievable with much less formal apparatus, often a short business plan and a convincing slide deck and demo can get people to a partner meeting if the time is right. But the criteria and process are much different, and ideas ready for public research grants are typically too early for VCs (but the EC wants to foster the creation VC-funded startups resulting from the disseminated research).