Any text field in which one is expected to enter a handle, use the input mode for URL, which most closely matches that of a handle. On mobile devices and any devices rendering a virtual keyboard, this will select a keyset optimized for URLs (prioritizing the . and .com keys) as well as turn off autocapitalization. Turning off autocorrect is also helpful for handle input fields.
https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Global_attributes/inputmode#url
This was completed in https://tangled.org/tranquil.farm/tranquil-pds/pulls/265/round/0, thanks for the suggestion!