When a decedent dies, an Erbengemeinschaft (heir partnership) is automatically formed of legal and named heirs. All heirs have an equal say regarding the decedent's estate.
An heir has extensive rights to information regarding the decedent's estate. An heir can request the decedent's last tax filing from the responsible tax office. (Swiss tax returns include a list of taxable assets (but some assets are excluded, e.g., pension assets). A public inventory can also be requested.
Cantonal law and regulations govern the procedures to follow to request a public inventory. The canton and possibly city where the decedent was legally resident should be approached.
As a example, these links are to regulations for Canton Aargau and city of Baden:
https://gesetzessammlungen.ag.ch/frontend/versions/666 https://www.baden.ch/de/leben-wohnen...entar.html/105
This is a link to Swiss Federal law on estate inventories, but the details are left to the cantons:
https://www.admin.ch/opc/en/classifi...042/index.html