About me: Male, 30 years, single, fulltime worker, no credit, no car, living in Norway with my parents. Looking to buy my first apartment.

I have converted from Norwegian Kroner to American Dollars. Numbers are rounded.

I have been able to save up $85K but I have set aside $14K for furniture and emergency, so my equity is per date $71K. I'm able to save up a minimum of $1.9K a month.
I always have the possibility to work overtime where I get an extra 50% on top of my hourly rate, but I'm not going to rely on working overtime every month in my calculations.

*Hourly rate gross income: $27
* Monthly net income: $2.9K
* 2021 gross income: $43.2K
* 2022 gross income: $59.4K

I have read about the 28% rule, and I'm not sure if this is something that is more of a general rule towards Americans, or if the same rule should also apply to Europe or Norway.
Achieving the 28% rule also seems to be very difficult. In my spreadsheet, if we take the example of the cheapest apartment ( $190K) and go in with $76K equity ( which I still need to save up for) it will take 30,58% of my $2850 monthly net income.
I have included the "common monthly cost" and "Municipal monthly cost" into that. This is something you would generally pay if you owe an apartment. I have set the "common monthly cost" at $238, and "Municipal monthly cost" at $79. I have not included electricity.
I also don't think an apartment in my area for $190K is realistic. I have no problem living outside the city (which I currently do) but an apartment for $237K - $285K seems to be more realistic in the area.
We are then reaching from 38% - 51% of my $2850 monthly net income depending on the equity.

I have been putting in some numbers in Excel which I have attached to the post. Housing price from $190K - $356K. Equity from $38K - $76K. To walk through some of the columns which probably isn't too clear, lets take the example of "Value of housing $261.250"

Net $2850: Mortgage + common + Municipal = Total month. This will display how much of my net income at $2850 a month will go to the "Total month" cost.
Difference step: Shows how much I'm saving for each step I go up with the equity. Example: I will be saving 3,49% if I go in with $66.5K instead of $57K.
Difference current to top: Shows how much I'm saving from the current Equity to the lowest equity. Example: I will be saving 10.13% if I go in with $76K compared to $38K.

My concern is:
Do I go all in with my equity to pay off the mortgage as fast as possible? Do I go in with lower equity and invest the rest? Perhaps a fund, or for a future rental apartment? All mortgage loans displayed in Excel is on 30 years.
Note, I'm no expert in this, and the numbers in the Excel could be terribly wrong. The prices of the loans is something I have gathered from a search engine in my country.