I'm a Canadian that's lived in the EU, and then moved to the UK just as they Brexited. Your statements here are inaccurate.
At irregular intervals, the EU is given more powers in order to have more power.
The EU is a collection of independent states who, through an ever-evolving complex array of treaties between those states have formed a cohesive union to pursue their collective interests. Each state makes its own decision to become a party to a treaty or not, and so what you might see as a singular union from the outside is actually a patchwork of agreements when you look closer.
At no point is the EU "given" power, nor is it taken. However, in the interests of the union in general, many of these treaties have non-negotiable requirements. Notoriously, membership in the customs union requires the freedom of movement, goods, and capital. Additionally, there's considerable pressure to applying members to join the Eurozone as that simplifies a lot
There is currently a debate about whether the 27 armies should be converted into a European army.
This is a great illustration of my point above. The EU does not have its own standing army. Instead, the member states have not seen any value in forming one... that is until recently when Russians started invading nations on its borders and the cohesive structure of NATO started falling apart. Now people are talking about it, and if the idea proves workable, some of the EU states will likely propose and possibly sign a treaty. It is highly unlikely that membership in the EU would automatically include membership in a defence union.
Canada would lose its powers and passing them on to the EU.
This is sort of true, but no more so than how we've given up our rights with other treaties. For example, were Canada to join the Schengen treaty, we'd have to allow passport-free access from Schengen member countries, in exchange for our rights to do the same. To reference a treaty you might be more familiar with, under NAFTA, Canada enjoyed a stable market for its oil exports to the US, but under that treaty, Canada's hands were tied when looking for non-US markets for that same oil. Like any treaty, it's a relationship with give-and-take, hopefully to the mutual benefit of both parties.
You would have to adopt the Euro as your currency and the European Central Bank would make interest rate policy.
This is likely, though as a member of the EU and Eurozone, Canada would have seats in the European Parliament, respresentation in the the European Commission, and would therefore have some influence on things like interest rate policy.
Conversely, consider the benefits of joining the Euro vs. our current situation where our currency is effectively tied to the US dollar because our economies are so tightly coupled. Consider the implications of tariff-free trade without currency conversions between 27 rich countries.
Of course there are more positive things, but you have to understand and accept that you would lose some of your independence.
This is the classic eurosceptic line: "but muh indententz!" It's a claim made in a vacuum of ignorance about how the world actually functions.
All EU member states are independent for some value of that term. Canada is economically and politically dominated by the US. They've bullied our government, crippled our industries, and even killed national projects like the Avro Arrow, and yet we still think of ourselves as "independent".
We live in a community of nations, and with that comes living with the understanding that we can't just invade other countries and take whatever resources we like. That's a restriction on our independence, but we don't see it that way because it's normalised. Similarly, Italy can't stop Germans from moving to Milan and setting up sausage restaurants, and the Dutch can't sell their own feta-like cheese and call it "feta" because it wasn't made in Greece. Sure that's an encroachment on their "independence", but it's a move that makes sense as it also means that Italians can live in France, and the Dutch can secure the rights to the name "gouda" in the markets of 27 member states.
It's not about giving away your independence. It's about forming a super-state with like-minded nations to grow your power as a collective and making that decision as an independent state.
I've lived in Vancouver, Ottawa, Toronto, Amsterdam, London, and Cambridge. I watched the UK tear itself from the Union and have seen first hand what a catastrophic act of self-harm that was, all in the name of "independence". The UK is now poorer, more xenophobic, and less safe. Were Canada ever offered the opportunity to join the EU, I should hope that we'd do better than the Brits.
It's a rather brilliant idea really, but when you consider the environmental implications of forcing web requests to ensure proof of work to function, this effectively burns a more coal for every site that implements it.