Good! I honestly had not thought about the Bios...Good find! I learned from it. Thanks!
Of note, I stumbled across info. indicating some Dell machines, including at least some production runs of my "old" Win 10 Pro Dell 3420, may be updatable to TPM 2.0 from TPM 1.2, and then Win 11 Pro can be installed without major issues. IF I can make the time, I may take a crack at that.
(I wouldn't need to buy a new machine for wifey.)
https://www.dell.com/support/kbdoc/en-us/000132757/tpm-option-is-missing-in-the-system-bios-setup-latitude-precision-or-xps