For anyone wanting to expand their S21 storage, I recommend portable SSDs from Samsung. Smaller than a credit card, connects directly to your phone, and optional password lock encryption on the drive.
Galaxy S21 Ultra 5G SM-G988U1 Support & Manual | Samsung Business
507750-S21 HP 500GB 7.2K RPM Midline SATA 3GBPS Hard Drive | Refurbished
Samsung Galaxy S21 Ultra 5G - 512 GB - Phantom Black - Unlocked
Hewlett-Packard (HP) MM0500FAMYT - 500GB 7.2K RPM 6G SAS SFF 2.5" Hard Disk Drive (HDD) - CPU Medics
Samsung Galaxy S21 Ultra 5G - 128 GB - Phantom Black - Unlocked
Samsung Galaxy S21 Ultra 5G, 512GB Black - Unlocked - Walmart.com
Samsung Galaxy S21 Ultra 5G Smartphone with a Snapdragon 888 5G processor | Qualcomm
Samsung Galaxy S21 Plus | Inland Cellular
HP 655708-S21 500 GB 2.5" Internal Hard Drive
Samsung Galaxy S21 Plus 5G SM-G996B/DS 256GB 8GB RAM International Version - Phantom Violet - Walmart.com
HP 600 GB 2.5" Internal - SAS
Samsung Galaxy S21 Ultra 5G - 512 GB - Phantom Black - Unlocked
HP 658071-S21 500GB SATA/600 Internal Hard Drive
Samsung Electronics Samsung Galaxy S21 Ultra 5G 512GB | Factory Unlocked Android Cell Phone | US Version 5G Smartphone | Phantom Black (Renewed)
458928-S21-RF HP 500GB 7200RPM SATA 3Gbps Midline Hot Swap 3.5-inch Internal Hard Drive
HP 655708-S21 500 GB 2.5" Internal Hard Drive
Samsung HM502JX pn: HM502JX C2371-F141-A13NQ sn:S21.. 500GB USB 2.0 B16-12 | eBay
Samsung Galaxy S21 5G - Features, Specs & Reviews | AT&T
Samsung Galaxy S21 FE 5G 256GB G990U Factory Unlocked- Graphite (Renewed)
SM-G998UZNFXAA | Galaxy S21 Ultra 5G 512GB (Unlocked) Phantom Brown | Samsung Business US
Amazon.com: 655708-S21 - 655708-S21 HP 500GB 7.2K 6G MDL SFF SATA SC HDD : Electronics
HP 507750-B21 500 GB 7.2K RPM SATA 3Gb/s 2.5 inch Internal Hard Drive
HP 507750-B21 500 GB 7.2K RPM SATA 3Gb/s 2.5 inch Internal Hard Drive
Samsung Galaxy S21 FE 5G 128GB Navy (Verizon) SM-G990UZBAVZW - Best Buy
MB0500GCEHE-SC HP 500GB 7200RPM SATA 6Gbps 3.5-inch Internal Hard Drive with Smart Carrier for G8 and G9 Server Systems
Samsung Galaxy S24 Ultra vs. S21 Ultra: Do you need to upgrade? | Digital Trends
Samsung Galaxy S21 Plus | Inland Cellular
