Oracle 18c

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with aux (vk, pc) as (
    select 'VK1', 'PC1' from dual union all
    select 'VK2', 'PC1' from dual union all
    select 'VK3', 'PC2' from dual union all
    select 'VK4', 'PC2' from dual union all
    select 'VK5', 'PC1' from dual union all
    select 'VK6', 'PC1' from dual union all
    select 'VK7', 'PC2' from dual union all
    select 'VK8', 'PC2' from dual),
aux1 (pc, a, maxi) as (
    select 'PC1', 'A1', 1 from dual union all 
    select 'PC1', 'A2', 2 from dual union all 
    select 'PC2', 'A1', 1 from dual union all 
    select 'PC2', 'A2', 2 from dual),
s as (
  select a.*,
    coalesce(sum(maxi) over(partition by pc order by pc, a 
      rows between unbounded preceding and 1 preceding), 0) + 1 as first_maxi,
    sum(maxi) over(partition by pc order by pc, a) as last_maxi
  from aux1 a
),
x as (
  select a.*,
    row_number() over(order by vk) as rn
  from aux a
),
y as (
  select a.*,
    (select count(*) from x b where b.rn <= a.rn and b.pc = a.pc) as cnt
  from x a
)
select
  y.vk, y.pc, s.a,
  case when s.pc is not null then row_number() 
    over(partition by y.pc, s.a order by y.rn) end as order_a_pc,
  case when s.pc is not null then row_number() 
    over(partition by y.pc order by y.rn) end as order_pc
from y
left join s on s.pc = y.pc and y.cnt between s.first_maxi and s.last_maxi
order by y.rn

VK	PC	A	ORDER_A_PC	ORDER_PC
VK1	PC1	A1	1	1
VK2	PC1	A2	1	2
VK3	PC2	A1	1	1
VK4	PC2	A2	1	2
VK5	PC1	A2	2	3
VK6	PC1	null	null	null
VK7	PC2	A2	2	3
VK8	PC2	null	null	null