A lot of countries that are declaring their readiness to take part in the peacekeeping mission are focusing on keeping the peace. Meaning that if the mission's mandate does not include peace enforcement tasks, the use of arms, — then such countries will gladly take part in it. If these tasks do appear there, I think the number of those willing to participate will drop rapidly, as these are rather critical things for the approval of political decisions on the national level.
Thinking about whether Ukraine needs a peacekeeping mission, I see no other way for it to get back its control over the occupied territory. We will not get there without a peacekeeping mission, just by ourselves.
The search for participants is a traditionally difficult task for each peacekeeping mission. Difficulties start from discussion of tasks to be included in the mandate: possibility of the use of arms, protection of civilians and peacekeepers themselves. Many countries will simply not agree to it. Difficulties also arise in connection with resource allocation and mission funding.