I tried using qutebrowser lately

dotjs2grease.rb

#!/usr/bin/env ruby
# klg, Aug 2020
# frozen_string_literal: true

files = {}
Dir[File.join(Dir.home, '.{js,css}/?*.{js,css}')].each do |ent|
  sta = File.stat(ent) # not lstat
  files[[sta.dev, sta.ino]] ||= []
  files[[sta.dev, sta.ino]] << ent
end

files.values.each do |paths|
  domains = paths.map { |x| x[%r{/([^/]+)\.(js|css)$}, 1] }
  domains.sort!
  type = paths[0][/\.([^.]+)$/, 1]
  out = "./dotjs-#{type}-#{domains[0]}.js"
  warn paths
  warn '-> ' + out
  File.open(out, 'w') do |f|
    f.write("// AUTOMATICALLY GENERATED FROM <#{paths[0]}>\n")
    f.write("// ==UserScript==\n")
    domains.each do |host|
      if host == 'default'
        f.write("// @include *\n")
      else
        f.write("// @match *://*.#{host}/*\n")
      end
    end
    f.write("// @run-at document-end\n")
    f.write("// ==/UserScript==\n\n")
    case type
    when 'js'
      IO.copy_stream(paths[0], f)
    when 'css'
      css = File.read(paths[0])
      css = css.gsub(/[\\$`]/) { |x| '\\' + x }
      css.chomp!
      f.write("document.head.appendChild(document.createElement('style')).innerText = `\n#{css}\n`\n")
    else
      raise
    end
  end
end