In order to be able to use a piano, all that is actually needed is a suitable seat and sufficient light for the respective requirement.
Accessories such as piano chandeliers, keys, metronome, keyboard cover pinch protection, etc. can be added as required. For the surface, depending on its condition, use only a feather duster or a lint-free cloth (do not use any harsh agents). For experienced piano owners, a soundboard cleaning rod set and a separate tuning key for small adjustments are also worthwhile.
To maintain the value of the piano, the humidity in the area where it is installed should be constantly monitored. In our experience, the commercially available, reasonably priced hygrometers sometimes show considerably incorrect values - it is worthwhile here as a really good instrument, in our experience, to take the testo 174H, for example, which is a so-called data logger for documenting the room climate and records the data. The proof can be important, because usually the owner is obliged to provide proof in case of warranty.
If necessary - especially during the heating period - a digitally controlled humidifier is required. We have had good experience with the AOS W2055D (now Boneco) - and for large rooms and longer absences with the AirTek PCMH45-WD.
With a moderator device (pedal or rope pull to lower a felt in front of the hammers) consideration for neighbours or sleeping people can be taken into account. This can be retrofitted relatively inexpensively by piano builders on most pianos. The installation of silent or self-playing systems can also be an option if this increases the joy of playing and usage. This Ladykracher sketch on YouTube uploaded by MySpass deals with the topic of too often/loud piano playing neighbours...