First of all, you can access and download the save file here:
https://drive.google.com/file/d/1HmwMV4ODUko9pSJ24uyooSV_b24yekYV/view?usp=sharing

This game is made in Godot engine, so you will have to reach where the engine keeps save data for any Godot game you may have played, located in the Roaming folder.

1. Press Win+R and enter %appdata% to immediately reach the Roaming folder, and locate the save location at Godot > app_userdata > Touhou- Gensokyo Survivors.
   
2. Alternatively just navigate to it manually through C:/Users/[Username]/AppData(Hidden item)/Roaming/Godot/app_userdata/Touhou- Gensokyo Survivors.
   
3. You probably already have a save.dat and settings.dat files in here. Rename or backup the existing save.dat file, and place your downloaded save file here.

This file will automatically unlock the most tedious and uninteresting achievements next time you start up the game:

• Mountain of Faith (10k faith, you most likely have this already unlocked anyways)
  
• Crystal Kleptomaniac (10k crystals)
  
• Fairy Shakedown (100k money. For reference, you need only 8k to unlock all characters, and after that you can blow up to 1650 to block 5 weapons from appearing each play. why.)
  
• Unresolvable Incident (100 gameovers)

This save file was created by compiling a modified version of the game that instead of creating a blank save file if there is none, creates one that automatically fulfills the conditions for the achievements.

Usually this would imply utilizing reverse engineering tools on the executable to extract back the project to be rewritten, but last year, the dev released the project as open source at https://github.com/XelophCode/Touhou_Survivors , so this is not necessary. Just download the entire repository as a ZIP.

You will need Godot_v4.1.3 to work with the project file. Head to touhou survivors > scripts > logic_ui > appdata.gd, at line 70 to see the variables and their values that a blank save file contains. Modify them to your liking (or anything else in the game, really. Hell, it's open source), and use Godot to extract/recompile the project back to an executable.
You will need to download extraction templates if you don't have them already, and make sure there is no save.dat in the Roaming folder so that it creates a new "blank" one.

The rest of achievements like encountering and surviving Daiyousei or gathering all spellcard combos at once are also tracked through the save file, but I didn't include them in the linked file as they were actually engaging to legitimately achieve.

Danmaku is about working smarter, not harder, after all!