I think you stated that the time horizon for early retirement you have in mind is 50? I'm ten years ahead of you but was also in the same headspace when I was in my late 20s.
At that stage I was renting but I'd say my pension was bigger than yours by roughly the value of the equity you've built up in the house (can't remember exactly, you may possibly be ahead in net worth terms at this stage). I was making similar money, and at some time around then got a promotion about in line with what you're expecting to get.
Fast forward to today and I am married with two small kids, bought & sold one house and subsequently bought a family home where I'm living now. In my estimation I'm well on track to be able to retire (or at least drastically reduce income) in my early 50s. I got to this position by maxing pension contributions and gradually increasing my income (substantially in the end).
I would suggest that you don't need to do anything particularly novel to achieve your goal. You are in quite a good position and are doing the right things. If you concentrate on clearing the mortgage and maxing your pension contributions you will be in a very strong position in ten years. I believe you can currently put 15% of your gross into your pension tax free? Does your employer make any contribution? Assuming you add €875 a month for the next 10 years you may be sitting somewhere around €270k, if your employer is adding say 4% then it would be €300k+ (see
here). In 20 years that may have grown to something like €800k. This assumes you don't increase your contribution to 20%/25% when you turn 30/40 (you should), and assumes no growth in income. If you work your way up to €100k PA income these numbers will be larger.
Your costs will grow if kids come into the equation (they're worth it), but your income should grow too. You should also bear in mind that you probably won't want to cash in the pension at 50, and should consider ways you might bridge the gap to, say, 60 while allowing that large pension pot to accumulate to an even bigger number.
You can use this site -
https://www.drcalculator.com/mortgage/ - to analyse the impact of additional payments to clearing the mortgage. Your current €67 overpayment reduces the term by ~2.5 years so you're still looking at almost 20 years to pay off the house. If you were somehow able to knock €50k off the principal when your fixed term ends that would come down to 11 years (assuming same interest rate), so you would be looking at a situation where your house is cleared off when you are 40. Knocking 25k off the balance would still get you down to 15 year repayment horizon. If you can manage that while maxing the pension you will be in great shape. This may be something to look at after the next fixed term comes to an end, rather than the current one, as someone in your position should prioritise having plenty of cash available over the next couple of years for reasons mentioned below.
As someone who dabbles in gambling you might be aware of the poker concept of 'FPS' (fancy play syndrome). There's no need to three-bet bluff on the river with top pair top kicker, just call and rake in the pot. This is possibly the situation you are in where you are looking for thin edges that you don't really need. Buying another property, EIIS schemes, buying land for solar leases etc - I don't think any of this is required for your goals and has a pretty big chance of damaging them.
Max your pension, set the extra aside and build up as much as you can to lop off the mortgage in 18 months' time, then see about what overpayments you can do to clear the mortgage as early as is financially comfortable while bearing in mind that there's a great chance you will want to have access to ready funds for things like marriage, kids, home improvements etc. Your income is not sufficiently high to ride things like this out if you've dumped all your excess into illiquid assets in an attempt to 'optimise'.
FWIW, I have a Money Makeover thread I posted when I was a few years older than you in which time I had gone from your position to having sold the first house, had the first kid, was thinking about a wedding and buying the current house. It might be of interest in seeing what the next few years might hold for you. I updated it recently with details from this year, so again may be of interest as a case study of where things may move for you in the next ten years.