/ n (M-x package-menu-filter-by-name) does exactly what you want, it filters only the package name, e.g., / n lsp-mode gets only the lsp-mode package.
/ n runs the command package-menu-filter-by-name (found in
package-menu-mode-map), which is an interactive compiled Lisp function
It is bound to / n, .
Try C-h P (M-x describe-package), it allows you filter by package names through the minibuffer. If you use helm-mode, it looks like
And in the *Packages* buffer, use Isearch and/or Occur, for example, to search packages start with lsp, use
M-s o ^ +lsp
M-s o is M-x occur.