Yes! LibreOffice Portable (download size ~250 MB) and OnlyOffice (desktop version ~200 MB) are lightweight, compatible with Microsoft formats, and completely free. For offline use on old PCs, AbiWord (for docs) and Gnumeric (for spreadsheets) are under 20 MB each.
Example XML (Word, Excel, PowerPoint only, 64-bit): download microsoft office highly compressed
<Configuration>
<Add OfficeClientEdition="64" Channel="MonthlyEnterprise">
<Product ID="O365ProPlusRetail">
<Language ID="en-us" />
<ExcludeApp ID="Access" />
<ExcludeApp ID="Publisher" />
<ExcludeApp ID="OneDrive" />
<ExcludeApp ID="Teams" />
<ExcludeApp ID="Outlook" />
<ExcludeApp ID="OneNote" />
</Product>
</Add>
</Configuration>
Result: Final install uses about 1.2 GB instead of 4 GB. Result: Final install uses about 1
Some repacks run silently in the background, using your CPU to mine Bitcoin or Monero. Your laptop becomes slow, overheats, and your electricity bill rises—all while the hacker profits. but safe and restorable.
If you have a valid product key, you can download the ISO from Microsoft (via their Volume Licensing Service Center or via regular retail links). Then compress it yourself using 7-Zip on Ultra + LZMA2 settings. You’ll get a file around 2.2 GB—still large, but safe and restorable.
Students and teachers with a valid school email (e.g., .edu) can get Office 365 Education for free, including the desktop apps. Download size is the same as retail, but fully legal and updated.
Your data, privacy, and peace of mind are worth far more than a risky 150 MB download.