Came here to post this too. Pandoc and a few lines of shell, all you need. Here is a super fancy Makefile:

  CONTENT_DIR  := content
  BUILD_DIR    := public
  MD_FILES := $(shell find $(CONTENT_DIR) -name '*.md')
  HTML_OUT := $(patsubst $(CONTENT_DIR)/%.md,$(BUILD_DIR)/%.html,$(MD_FILES))
  .PHONY: all clean assets serve
  
  all: $(HTML_OUT) assets
  assets:
   @mkdir -p $(BUILD_DIR) && cp -a static/style.css $(BUILD_DIR)/
  $(BUILD_DIR)/%.html: $(CONTENT_DIR)/%.md templates/default.html site.yaml
   @mkdir -p $(dir $@)
   pandoc --standalone --from gfm --to html5 \
     --template=templates/default.html \
     --metadata-file=site.yaml \
     --toc --toc-depth=3 \
     -o $@ $<

Ask ChatGPT, it'll spit out the rest (sample posts, template, CSS, YAML, Makefile, etc)