KOReader userpatch to show info in the file browser title

2-fm-title-info.lua

-- KOReader userpatch to show info in the file browser title

local config = {
    -- indicators, comment out unneeded and set the order
    "wifi",
    "memory", -- RAM used, MiB
    "storage", -- free storage, requires SystemStat plugin
    "text",
    "battery",
    "ctime",

    -- settings, comment out or set a value
    text = "KOReader",
    separator = " | ", -- | • ·
    wifi_show_disabled = true,
    bold = false,
}

local BD = require("ui/bidi")
local Device = require("device")
local FileManager = require("apps/filemanager/filemanager")
local NetworkMgr = require("ui/network/manager")
local datetime = require("datetime")
local Screen = Device.screen

local string_func = {
    text = function()
        return config.text
    end,
    ctime = function()
        return datetime.secondsToHour(os.time(), G_reader_settings:isTrue("twelve_hour_clock"))
    end,
    wifi = function()
        return NetworkMgr:isWifiOn() and "" or (config.wifi_show_disabled and "")
    end,
    battery = function()
        if Device:hasBattery() then
            local powerd = Device:getPowerDevice()
            local batt_lvl = powerd:getCapacity()
            local batt_symbol = powerd:getBatterySymbol(powerd:isCharged(), powerd:isCharging(), batt_lvl)
            local text = BD.wrap(batt_symbol) ..  BD.wrap(batt_lvl .. "%")
            if Device:hasAuxBattery() and powerd:isAuxBatteryConnected() then
                local aux_batt_lvl = powerd:getAuxCapacity()
                local aux_batt_symbol = powerd:getBatterySymbol(powerd:isAuxCharged(), powerd:isAuxCharging(), aux_batt_lvl)
                text = text .. " " .. BD.wrap("+") .. BD.wrap(aux_batt_symbol) ..  BD.wrap(aux_batt_lvl .. "%")
            end
            return text
        end
    end,
    storage = function(self)
        if self.systemstat then
            local userpatch = require("userpatch")
            local SystemStat = userpatch.getUpValue(self.systemstat.addToMainMenu, "SystemStat")
            if SystemStat then
                SystemStat.kv_pairs = {}
                SystemStat:appendStorageInfo()
                return SystemStat.kv_pairs[3][2]
            end
        end
    end,
    memory = function()
        local statm = io.open("/proc/self/statm", "r")
        if statm then
            local _, rss = statm:read("*number", "*number")
            statm:close()
            return rss and ("%d"):format(math.floor(rss / 256))
        end
    end,
}

function FileManager:updateTitleBarTitle()
    local strings = {}
    for _, item in ipairs(config) do
        local text = string_func[item](self)
        if text then
            table.insert(strings, text)
        end
    end
    self.title_bar:setTitle(table.concat(strings, config.separator or " "))
end

FileManager.onNetworkConnected    = FileManager.updateTitleBarTitle
FileManager.onNetworkDisconnected = FileManager.updateTitleBarTitle
FileManager.onCharging            = FileManager.updateTitleBarTitle
FileManager.onNotCharging         = FileManager.updateTitleBarTitle
FileManager.onResume              = FileManager.updateTitleBarTitle
FileManager.onTimeFormatChanged   = FileManager.updateTitleBarTitle

function FileManager:onPathChanged(path)
    if not self.title_info_update_time_s then -- first run
        self.title_info_update_time_s = 0
        if config.bold == false then
            self.title_bar.title_face = self.title_bar.info_text_face
            self.title_bar.bottom_v_padding = self.title_bar.bottom_v_padding + Screen:scaleBySize(5)
            self.title_bar:clear()
            self.title_bar:init()
        end
    end
    local now = os.time()
    if now > self.title_info_update_time_s + 60 then
        self.title_info_update_time_s = now
        self:updateTitleBarTitle()
    end
    self:updateTitleBarPath(path) -- subtitle
end

I have a new version with the relevant menu to configure all the settings, choose which items to show, and rearrange the items.