ᐅ Complete Renovation and Modernization of a House in 1986 – What Were the Costs?

Hello community, I would like to ask for your assessment and experience once again.
We are considering buying a house from 1966 with approximately 160m² (1,722 sq ft). The location is unique for us.
The condition of the building is good.
We can contribute with our own work for the core renovation, demolition of the old roof, creating openings, etc.
We will definitely involve an architect with a structural engineer or a building contractor.

We have big plans and would like a rough estimate of the costs we should expect:

- Roof/attic extension of about 110m² (1,184 sq ft), open to roof style, with photovoltaic panels
- New heating system (probably heat pump with underfloor heating)
- All windows on the ground floor (including a panoramic window)
- All windows on the upper floor (extension with panoramic window)
- Various wall openings
- Staircase renewal to the upper floor
- Conversion of a small room into an entrance area with a front door
- New electrical wiring, water pipes, and sewage pipes
- Exterior wall insulation
- New double garage

There are no available building plots in our region.
Would you recommend demolition and new construction for our project?
Or could the project be worthwhile with good planning?

Thanks for all tips, experiences, and cost estimates.