SuperTable queries on fields in fields
I think I followed this breakdown, but a screenshot of the admin could be helpful as well if this answer isn't accurate...
{% set speakers = entry.eventSpeakerList.all() %}

{% for speaker in speakers %}
    {# Get the session entries for each speaker row #}
    {% for session in speaker.sessions.all() %}

        {# Get the person entries for each session #}
        {% for person in session.sessionSpeaker.all() %}
            &lt;a href=&quot;#s{{ person.id }}&quot;&gt;
        {% endfor %}
    {% endfor %}
{% endfor %}

This is likely the first step to confirm it's getting the value you need. There are a couple of optimizations that we can make depending upon if there can only ever be a single session related to a speaker and if only a single person can be related to a session.
{% set speakers = entry.eventSpeakerList.all() %}

{% for speaker in speakers %}
    {% set session = speaker.sessions.one() %}
    {% set person = session.sessionSpeaker.one() %}

    &lt;a href=&quot;#s{{ person.id }}&quot;&gt;
{% endfor %}

The next step would be to optimize the performance, by taking advantage of Eager Loading.
{% set speakers = entry.eventSpeakerList.with([
    'sessions',
    'sessions.sessionSpeaker',
]).all() %}

Then, that means you are getting arrays back instead of Element Queries. So something like this should work (against assuming only one session and one person is allowed in those respective entries fields)
{% set speakers = entry.eventSpeakerList.with([
    'sessions',
    'sessions.sessionSpeaker',
]).all() %}

{% for speaker in speakers %}
    {% set session = speaker.sessions[0] ?? null %}
    {% set person = session.sessionSpeaker[0] ?? null %}

    &lt;a href=&quot;#s{{ person.id }}&quot;&gt;
{% endfor %}


Ok, here's an updated version after seeing the Admin UI, not sure if those field names are exactly right, since I can't tell from that UI:
{# Get all the super table rows and eager load the sessions and speakers #}
{% set scheduleSuperTable = entry.scheduleSuperTable.with([
    'sessions',
    'sessions.sessionSpeaker',
]).all() %}

{# Loop through the rows #}
{% for row in scheduleSuperTable %}
    {{ row.eventDay }}
    {{ row.timeSlot }}

    {# Assuming there can only be one session #}
    {% set session = row.sessions[0] ?? null %}

    {% if session %}
        {{ session.title }}

        {# Loop through all of the speakers in the session #}
        {% for speaker in session.sessionSpeaker %}
            {{ speaker.id }}
            {{ speaker.title }}
        {% endif %}
    {% endif %}
{% endfor %}