Good news: Yesterday evening, 2024-12-18, the new version iodéOS 5.8 became available and I installed it right away.
Now it works: “Google Sheets” as well as “Google Docs” and “Google Drive” apps.
I think the miracle is behind this line in the Changelog: “Signature spoofing fixed to support lastest versions of Goggle applications.” Thank you @vince31fr and all involved developers! What a X-mas gift for me 
I will update (Editable list) Apps compatible with iodéOS accordingly.