The unit's own counters, on every mapped board. The hydro board keeps lifetime counters, the ones the user interface shows under operating hours and energy data: the heat produced since the installation, the compressor hours in space heating, cooling and hot water, the pump hours and the compressor starts. They are now read once a minute and published as lifetime totals ("Unit meter: Heat produced (kWh)", "Unit meter: Compressor hours, space heating (h)", "… space cooling (h)", "… hot water (h)", "Unit meter: Pump hours (h)", "Unit meter: Compressor starts") on every hydro board software ESPAltherma knows the targets of, plus 19016505 and 23015103. Started by @ppuetsch on 20002203 (#647), checked against the interface there and on an 18002904; the other softwares come from the boards' own code, a first comparison with your interface's screens is welcome. Read-only. What is known of the 20002203 board's memory: doc/memory-20002203.md.
Targets in the unit's working memory only. Settings → Experimental → "Keep the targets in the unit's working memory only": for a target an automation changes all day (price, solar surplus), the unit's memory is never written and keeps its own curve; ESPAltherma holds the target and writes it again within two minutes when a restart of the heat pump (or a save on its interface) brings the curve back, as the power limit does. The hold survives a restart of ESPAltherma. Contributed by @ppuetsch (#643), tested through a real heat pump restart. With that box ticked, the leaving water range goes up to the unit's own maximum ([9-00]) instead of 45 °C: the 45 is the interface's rule for the mild point of the curve, not the unit's (#648, @Ville-VeikkoH).
HT: the hot water tank and the 3-way valve. On the HT outdoor unit's board, two more values from the frames between the hydrobox and the outdoor unit: "E0: DHW tank (C)" (null when the unit has no tank sensor) and "E0: 3-way valve DHW" (1 = hot water). Contributed by @selman61 (#638); the valve bit is not yet confirmed on a unit with a tank. doc/diii.md describes the reader.
20017701 (EHSXB08P50EF, the 4-8 kW ECH2O on their earlier software): targets and power limit, from a memory dump by @forTT78 (#642), awaiting his first report.
Time server. Settings → This device → "Time server": a local NTP server for a network kept off the Internet (#645, @Jeltel). Takes effect at the next restart.
Statistics. A restart of the board (an update) during a compressor run no longer counts as a start (@ppuetsch, #650).
New Home Assistant entities: the five "Unit meter: …" counters on the boards mapped for them, the two HT values.
Update: System → Firmware update → Check for an update, or the web installer.