Something along the lines of:
ht.select(
"locus",
"alleles",
gnomad_ac=ht.freq[0].AC,
gnomad_af=ht.freq[0].AF,
gnomad_an=ht.freq[0].AN,
gnomad_homozygote_count=ht.freq[0].homozygote_count,
).export("/path/to/export.tsv")
To include more columns, include expressions for them in the select
call.