It's very much the same for OpenSSL 3.0.0: libssl.so and libcrypto.so.

$ ldd build/lib.linux-x86_64-3.10/_ssl.cpython-310-x86_64-linux-gnu.so 
        linux-vdso.so.1 (0x00007ffffa3cc000)
        libssl.so.3 => /home/heimes/dev/python/multissl/openssl/3.0.0-alpha12/lib/libssl.so.3 (0x00007f1ab0b66000)
        libcrypto.so.3 => /home/heimes/dev/python/multissl/openssl/3.0.0-alpha12/lib/libcrypto.so.3 (0x00007f1ab06b1000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f1ab065f000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f1ab0494000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f1ab048d000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f1ab0c55000)


The external engines and OSSL providers are external plugins. They are very much akin to Python's extension modules. OpenSSL loads them with dlopen(), dlsym()s an init function and finally calls the init function. It uses either RTLD_NOW or RTLD_NOW | RTLD_GLOBAL dlopen() flags.

The engines and OSSL providers depend on libcrypto.so. AFAIK this won't play will with static linking.

$ ldd ../multissl/openssl/3.0.0-alpha12/lib/engines-3/afalg.so 
        linux-vdso.so.1 (0x00007fffa417d000)
        libcrypto.so.3 => /home/heimes/dev/python/multissl/openssl/3.0.0-alpha12/lib/libcrypto.so.3 (0x00007fbcb3c75000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007fbcb3c3e000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fbcb3c1c000)
        libc.so.6 => /lib64/libc.so.6 (0x00007fbcb3a51000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fbcb4133000)

$ ldd ../multissl/openssl/3.0.0-alpha12/lib/ossl-modules/legacy.so 
        linux-vdso.so.1 (0x00007ffd3ccc0000)
        libcrypto.so.3 => /home/heimes/dev/python/multissl/openssl/3.0.0-alpha12/lib/libcrypto.so.3 (0x00007f5524f36000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f5524eff000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f5524edd000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f5524d12000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f5525419000)