Installing to flash disk gives you an option to install with an "n" option. Once installed in this manor the drive is protected from any changes, a reboot reverts the drive to just as it was. Now is there a way to change the umask=000 so that the drive can have changes made from time to time but locked down the rest of the time. I have young students that use the notebooks and the write protection is great until I need to add something.
ACASIS 2.5/3.5 inch 2 Bay SATA USB 3.0 Hard Drive Disk HDD SSD Enclosure 4 RAID
$58.99
M.2 NVME SATA SSD Enclosure USB 3.2 Gen 2 10Gbps for M-Key or M+B Key SSD to 8TB
$40.86
804625-B21 HPE 800GB SATA 6G MIXED USE SFF (2.5IN) SC SSD 805381-001
$67.00
SanDisk 2TB Ultra 3D NAND SSD, Internal Solid State Drive - SDSSDH3-2T00-G26
$149.99
Patriot P210 128GB 256GB 512GB 1TB 2TB 2.5" SATA 3 6GB/s Internal SSD PC/MAC Lot
$14.99
Micron 5100 MAX 120GB SATA 6Gb/s 2.5" Internal SSD MTFDDAK120TCC Solid State
$9.99
Intel DC S3510 Series 120GB SSD 2.5" 6Gb/s SATA Solid State Drive SSDSC2BB120G6K
$9.99
Netac 1TB 2TB 512GB Internal SSD 2.5'' SATA III 6Gb/s Solid State Drive lot
$13.99
Fanxiang SSD 512GB 1TB 2TB 4TB 2.5'' SSD SATA III Internal Solid State Drive lot
$198.99
Fanxiang 256GB 512GB 1TB 2TB 4TB Internal SSD 2.5" SATA III 6GB/s for PC/MAC Lot
$188.09