From what I could garner reading the support lifecycles, there is no way you get support for Microsoft(nee Office) 365 on Win10 past Oct 2025, not even on LTSC or IoT versions. But there are a few options:

0.) Do a supported Upgrade to Win11, if your hardware allows. (see also point # 4)

1.) Move from Microsoft(nee Office) 365 to Windows 365. That way, you get a Win11 instance in the cloud with all the goodies, AND, since the machine you use to access your Win11 cloud instance is Win10, you get 3 years of ESU thrown in (so, your “Thin Terminal” is secure). That way, you can use whatever is still supported on Win10 (say, steam) on Win10, and do the non supported stuff on your cloudy machine. There is a price differential.

2.) Go to WinServer22 and have your Microsoft(nee Office) 365 stuff supported until 2029 (and the OS itself until 2033). This is legal, and thanks to online key sellers, is reletively cheap.

3.) Move to Office 2021, support ends latter (but I do not remember exactly when, and with which versions of Win10). This is expensive, perhaps the online key vendors can help again.

4.) Upgrade your machine with free Firmware (for the fTPM/PTT) and used parts (say, a 7th gen intel or AMD Zen2) to resemble as much as possible a machine supported by Win11 and do an upgrade to that.

5.) Run a Win11 instance in a SECURE OS (be it Linux, BSD, Win10 ESU, Win10LTSC 2019, Win10 IoT 2021 or WinServer 2022, or Baremetal) and run your Microsoft(nee Office) 365 there. Be carefull as some SW does not like to be run on a VM (certain games in particular). Run the Win10 stuff in native Win10 and the non supported stuff on virtual Win11.

Finally, be this a reminder that, even with ESU supported until 2028, Win10 LTSC 2019 supported until 2030, IoT 2021 supported until 2032, and Server 2022 supported until 2033, Win10 support is just as good as the support your software vendors want to give to the software you want to run. Meaning that if Steam, Epic, GoG, Adobe, et al decide to stop supporting Win10 after a certain dealine, you will have a fully supported Win10 instance that will not be able to run the SW you want in a secure and stable manner (because the SW itself will be unsupported).

Start planning now, you/we only have 10 months.