I use Gentoo on a few machines, and I'm confused by what GP says: I have no problems using OpenSSL 3, and the 1.1 releases have been masked (not installable by default) for a while now.
The following mask changes are necessary to proceed:
(see "package.unmask" in the portage(5) man page for more details)
# required by net-libs/nodejs-20.5.1::gentoo
# required by www-client/firefox-102.15.0::gentoo
# required by @selected
# required by @world (argument)
=dev-libs/openssl-1.1.1v
And many many many more packages. I went through like 20 yesterday and created custom ebuilds without mentions to slot :0= in ebuild, but there is plenty more.
Something seems unusual about your system. Are you using an unusual profile or heavily customized make.conf? net-libs/nodejs-20.5.1 is satisfied with dev-libs/openssl-3.0.10 out of the box here.
I have a fully updated world with a KDE desktop, and don't have OpenSSL 1.1 installed at all.
eselect profile list says I have selected the default one: default/linux/amd64/17.1 (stable) *
I would not say it is something unusual...
But funny thing is that if I emerge that one specific package with -1, it does not pull this dependency. It seems like something broken inside the portage.
I experienced a similar sounding issue, but was able to decipher the blocked emerge output from portage to find that app-crypt/tpm2-tss-engine was blocking the whole system from getting onto openssl-3. Once I dropped tpm2-tss-engine, things went forward swimmingly. No other unmasking/masking of anything was needed.
It seems like portage did remember that those packages were built against that openssl version - when running as "emerge -DavuUN @world @system --changed-deps" the problem went away :-)
Probably some caching issue/race condition in portage...
Gentoo is very much alive - from time to time I try some other distro but I keep going back. I do some development and I need headers and generally latest versions of some libraries and in Gentoo this is by default.
In Debian there is no way to do that - and the last time I tried to switch to unstable, my Debian commited suicide :)
But being behind Debian Stable on up to date packaging doesn't look great...